* Synopsys DesignWare PCIe interface

Required properties:
- compatible:
	"snps,dw-pcie" for RC mode;
	"snps,dw-pcie-ep" for EP mode;
- reg: For designware cores version < 4.80 contains the configuration
       address space. For designware core version >= 4.80, contains
       the configuration and ATU address space
- reg-names: Must be "config" for the PCIe configuration space and "atu" for
	     the ATU address space.
    (The old way of getting the configuration address space from "ranges"
    is deprecated and should be avoided.)
RC mode:
- #address-cells: set to <3>
- #size-cells: set to <2>
- device_type: set to "pci"
- ranges: ranges for the PCI memory and I/O regions
- #interrupt-cells: set to <1>
- interrupt-map-mask and interrupt-map: standard PCI
	properties to define the mapping of the PCIe interface to interrupt
	numbers.
EP mode:
- num-ib-windows: number of inbound address translation windows
- num-ob-windows: number of outbound address translation windows

Optional properties:
- num-lanes: number of lanes to use (this property should be specified unless
  the link is brought already up in BIOS)
- reset-gpio: GPIO pin number of power good signal
- clocks: Must contain an entry for each entry in clock-names.
	See ../clocks/clock-bindings.txt for details.
- clock-names: Must include the following entries:
	- "pcie"
	- "pcie_bus"
- snps,enable-cdm-check: This is a boolean property and if present enables
   automatic checking of CDM (Configuration Dependent Module) registers
   for data corruption. CDM registers include standard PCIe configuration
   space registers, Port Logic registers, DMA and iATU (internal Address
   Translation Unit) registers.
RC mode:
- num-viewport: number of view ports configured in hardware. If a platform
  does not specify it, the driver assumes 2.
- bus-range: PCI bus numbers covered (it is recommended for new devicetrees
  to specify this property, to keep backwards compatibility a range of
  0x00-0xff is assumed if not present)

EP mode:
- max-functions: maximum number of functions that can be configured

Example configuration:

	pcie: pcie@dfc00000 {
		compatible = "snps,dw-pcie";
		reg = <0xdfc00000 0x0001000>, /* IP registers */
		      <0xd0000000 0x0002000>; /* Configuration space */
		reg-names = "dbi", "config";
		#address-cells = <3>;
		#size-cells = <2>;
		device_type = "pci";
		ranges = <0x81000000 0 0x00000000 0xde000000 0 0x00010000
			  0x82000000 0 0xd0400000 0xd0400000 0 0x0d000000>;
		interrupts = <25>, <24>;
		#interrupt-cells = <1>;
		num-lanes = <1>;
	};
or
	pcie: pcie@dfc00000 {
		compatible = "snps,dw-pcie-ep";
		reg = <0xdfc00000 0x0001000>, /* IP registers 1 */
		      <0xdfc01000 0x0001000>, /* IP registers 2 */
		      <0xd0000000 0x2000000>; /* Configuration space */
		reg-names = "dbi", "dbi2", "addr_space";
		num-ib-windows = <6>;
		num-ob-windows = <2>;
		num-lanes = <1>;
	};