* Renesas RCar PCIe interface

Required properties:
compatible: "renesas,pcie-r8a7779" for the R8A7779 SoC;
	    "renesas,pcie-r8a7790" for the R8A7790 SoC;
	    "renesas,pcie-r8a7791" for the R8A7791 SoC;
	    "renesas,pcie-r8a7793" for the R8A7793 SoC;
	    "renesas,pcie-r8a7795" for the R8A7795 SoC;
	    "renesas,pcie-rcar-gen2" for a generic R-Car Gen2 compatible device.

	    When compatible with the generic version, nodes must list the
	    SoC-specific version corresponding to the platform first
	    followed by the generic version.

- reg: base address and length of the pcie controller registers.
- #address-cells: set to <3>
- #size-cells: set to <2>
- bus-range: PCI bus numbers covered
- device_type: set to "pci"
- ranges: ranges for the PCI memory and I/O regions.
- dma-ranges: ranges for the inbound memory regions.
- interrupts: two interrupt sources for MSI interrupts, followed by interrupt
	source for hardware related interrupts (e.g. link speed change).
- #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.
- clocks: from common clock binding: clock specifiers for the PCIe controller
	and PCIe bus clocks.
- clock-names: from common clock binding: should be "pcie" and "pcie_bus".

Example:

SoC specific DT Entry:

	pcie: pcie@fe000000 {
		compatible = "renesas,pcie-r8a7791", "renesas,pcie-rcar-gen2";
		reg = <0 0xfe000000 0 0x80000>;
		#address-cells = <3>;
		#size-cells = <2>;
		bus-range = <0x00 0xff>;
		device_type = "pci";
		ranges = <0x01000000 0 0x00000000 0 0xfe100000 0 0x00100000
			  0x02000000 0 0xfe200000 0 0xfe200000 0 0x00200000
			  0x02000000 0 0x30000000 0 0x30000000 0 0x08000000
			  0x42000000 0 0x38000000 0 0x38000000 0 0x08000000>;
		dma-ranges = <0x42000000 0 0x40000000 0 0x40000000 0 0x40000000
			      0x42000000 2 0x00000000 2 0x00000000 0 0x40000000>;
		interrupts = <0 116 4>, <0 117 4>, <0 118 4>;
		#interrupt-cells = <1>;
		interrupt-map-mask = <0 0 0 0>;
		interrupt-map = <0 0 0 0 &gic 0 116 4>;
		clocks = <&mstp3_clks R8A7791_CLK_PCIE>, <&pcie_bus_clk>;
		clock-names = "pcie", "pcie_bus";
		status = "disabled";
	};