First set of new IIO device support, fatures and cleanups for the 5.7 cycle

Includes changes for the counter subsystem

Core Feature
* Explicitly handle sysfs values in dB, including correctly handling the
  needed postfix dB.
* Add a TODO to suggest suitable activities for new contributors to IIO now
  the vast majority of drivers are out of staging (and the remaining ones
  there are 'hard'). Also update the TODO in staging to remove stale entries.

Staging graduations
* ad7192 ADC.

New device support
* ad5770r
  - New driver for this 6 channel DAC including DT bindings.
* ad8366
  - Add supprot for the hmc1119 attenuator.
* al3010
  - New driver supporting this Dyna-image light sensors.
  - Power management and DT bindings added in additional patches.
* atlas-sensor
  - Add support for atlas DO-SM device.  Reads disolved oxygen in a solution.
* gpap002x00f
  - New driver and bindings to support the GP2AP002A00F and GP2AP002S00F light
    and proximity sensors. There is some limited existing support in
    input.  The intent is to drop this driver once IIO driver is in place.
* hmc425a
  - New driver for this attenuator.
* icp10100
  - New driver for this presure sensor.
* ltc2632
  - Add support for the ltc2636 8 channel DAC. Includes bindings and some
    tidying up of the driver.
* inv_mpu6050
  - Support IAM20680, ICM20609, ICM20689 and ICM20690.
    Includes related tidy up and rework of low pass filter bandwidth
    handling to give suitable values for all chips.

Binding conversions to yaml or missing bindings docs.
* atlas-sensor, including consolidation of previous 3 separate docs into 1.
* ad7923, previously no doc.
* max1363, split into max1238 and max1363 to simplify yaml.
* stm32-adc

Features
* (counter) 104-quad-8
  - Support a filter clock prescaler.
  - Support reporting of encoder cable status.
* ad7124
  - Low pass filter support.
  - Debugfs interface to access registers directly.
* ad8366
  - Support control of hardware gain.
* inv_mpu6050
  - Runtime pm with autosuspend.
* npcm adc
  - Add reset support. This is a breaking change if DT is not in sync,
    however this device is a BMC so the ecosystem is closed enought that
    this should not be a problem.
* srf04
  - Add power management with DT bindings for the GPIO.
* stm32-timer-trigger
  - Power management.
* (counter) stm32-timer-cnt
  - Power management.
* vcnl4000
  - Enable runtime PM for devices that don't use on demand measurement.

Cleanups and minor fixes
* core
  - Avoid double read when using debugfs.  Whilst we provide no guarantees
    on lack of side effects using the debugfs interfaces, this one is
    generate unexpected results so let us tidy it up.
* dac/Kconfig
  - Alphabetic order.
* ad5755
  - Grammar and minor other fixes.
* ad7124
  - Fail probe if get_voltage fails as no meaningful readings can be had
    without knowing the external reference.
  - Switch to selection between different channel attributes rather than
    building the arrays at runtime.
  - Remove the spi_device_id table as the driver cannot be probled without
    more information that can be provided without dt.
  - Update sysfs docs to provide more inormation and bring remaining docs for
    this part out of staging.
* ad9292
  - Use new SPI transfer delay structure.
* adis library
  - Add unlocked version of adis_initial_startup and refactor the function.
  - Add a product ID santiy check.
  - Add support for different self test registers.
  - Use new SPI delay structure.
  - Add new docs and tidy up existing.
* adis16136
  - Initialize adis_data statically.
* adis16400
  - Initialize adis_data statically.
* adis16460
  - Use core __adis_initial_Startup now it supports everything needed.
* adis16480
  - Initialize adis_data statically.
  - Use core __adis_initial_startup now it supports everything needed.
* al3320a
  - Add missing DT binding docs.
  - Tidy up code formatting.
  - Simplify error paths using devm_add_action_or_reset.
  - Ensure autoloading works by adding the of_match_table.
* atlas-sensor
  - Drop false requirement for interrupt line, the value can be polled using
    a sysfs or hrtimer type trigger.
* exynos-adc
  - Silence warning message on deferring probe.
* gp2ap002
  - Greatly simplify the Lux LUT.
  - Reorder actions around buffer setup and tear down as part of a sub-system
    wide standardization of these.
* inv_mpu6050
  - Various lttle tidyups.
  - Simpliy I2C aux MUX handling by enabling it only at startup. It never
    needs to be disabled.
  - Simplify polling rate when magnetometer enabled by putting only under
    control of userspace.
  - Always execute full reset on devices supporting spi. It does no harm
    when using i2c and makes for simpler code.
  - Reduce over the top sleep times for vddio regulator power up.
  - Greatly simplify power and engine management.
  - Fix some delays in polled reads (only visible due to other changes)
  - Stop preventing sampling rate changes whilst running as there is no
    adverse consequence of doing so.
  - Prevent attempting to read the temperature if neither accel nor
    gyro is enabled.
* lmp9100
  - Reorder actions around buffer setup and tear down as part of a sub-system
    wide standardization of these.
* max1118
  - Use new SPI transfer delay structure.
* mcp320x
  - Use new SPI transfer delay structure.
* si1133
  - Read full 24 bit signed integer instead o dropping last 8 bits of value.
    Not a critical fix as just adds precision.
* st_sensors
  - Use st_sensors_dev_name_probe instead of open coded version in st_accel
  - Handle potential memory allocation failure.
* st_lsm6dsx
  - Fix some wrong structure element naming in documentation.
  - Add missing return value check.
* stm32_timer_cnt
  - Drop some unused left over IIO headers from this count subsystem driver.
  - Ensure the clock is enabled in master mode.  Theoretical issue rather
    than one known to happen in the wild.
* tlc4541
  - Use new SPI delay structure.
-----BEGIN PGP SIGNATURE-----
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=20Uc
-----END PGP SIGNATURE-----