dt-bindings: PCI: Add DT bindings for PCI designware EP mode

- reg-names: Must be "config" for the PCIe configuration space.

    (The old way of getting the configuration address space from "ranges"

    is deprecated and should be avoided.)

- num-lanes: number of lanes to use

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

- interrupt-map-mask and interrupt-map: standard PCI

	properties to define the mapping of the PCIe interface to interrupt

	numbers.

- num-lanes: number of lanes to use

EP mode:

- num-ib-windows: number of inbound address translation

        windows

- num-ob-windows: number of outbound address translation

        windows

Optional properties:

- num-viewport: number of view ports configured in hardware.  If a platform

  does not specify it, the driver assumes 2.

- 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

- 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)

- 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"

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: