chrome platform changes for 5.20

cros_ec_proto:
* Leverage Kunit and add Kunit test cases.
* Clean-ups.
* Fix typo.

cros_ec_commands:
* Fix typo.
* Fix compile errors.

cros_kbd_led_backlight:
* Support OF match.
* Support EC PWM backend.

cros_ec:
* Always expose the last resume result to fix sleep hang detection on
  ARM-based chromebooks.

wilco_ec:
* Fix typo.

cros_ec_typec:
* Clean-ups.
* Use Type-C framework utilities to manage altmode structs.
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