dt-bindings: pci: add DT binding for Marvell Armada 7K/8K PCIe controller

* Marvell Armada 7K/8K PCIe interface

This PCIe host controller is based on the Synopsis Designware PCIe IP

and thus inherits all the common properties defined in designware-pcie.txt.

Required properties:

- compatible: "marvell,armada8k-pcie"

- reg: must contain two register regions

   - the control register region

   - the config space region

- reg-names:

   - "ctrl" for the control register region

   - "config" for the config space region

- interrupts: Interrupt specifier for the PCIe controler

- clocks: reference to the PCIe controller clock

Example:

	pcie@f2600000 {

		compatible = "marvell,armada8k-pcie", "snps,dw-pcie";

		reg = <0 0xf2600000 0 0x10000>, <0 0xf6f00000 0 0x80000>;

		reg-names = "ctrl", "config";

		#address-cells = <3>;

		#size-cells = <2>;

		#interrupt-cells = <1>;

		device_type = "pci";

		dma-coherent;

		bus-range = <0 0xff>;

		ranges = <0x81000000 0 0xf9000000 0  0xf9000000 0 0x10000	/* downstream I/O */

			  0x82000000 0 0xf6000000 0  0xf6000000 0 0xf00000>;	/* non-prefetchable memory */

		interrupt-map-mask = <0 0 0 0>;

		interrupt-map = <0 0 0 0 &gic 0 GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>;

		interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>;

		num-lanes = <1>;

		clocks = <&cpm_syscon0 1 13>;

		status = "disabled";

	};