Socionext UniPhier PCIe PHY bindings

This describes the devicetree bindings for PHY interface built into
PCIe controller implemented on Socionext UniPhier SoCs.

Required properties:
- compatible: Should contain one of the following:
    "socionext,uniphier-pro5-pcie-phy" - for Pro5 PHY
    "socionext,uniphier-ld20-pcie-phy" - for LD20 PHY
    "socionext,uniphier-pxs3-pcie-phy" - for PXs3 PHY
- reg: Specifies offset and length of the register set for the device.
- #phy-cells: Must be zero.
- clocks: A list of phandles to the clock gate for PCIe glue layer
	including this phy.
- clock-names: For Pro5 only, should contain the following:
    "gio", "link" - for Pro5 SoC
- resets: A list of phandles to the reset line for PCIe glue layer
	including this phy.
- reset-names: For Pro5 only, should contain the following:
    "gio", "link" - for Pro5 SoC

Optional properties:
- socionext,syscon: A phandle to system control to set configurations
	for phy.

Refer to phy/phy-bindings.txt for the generic PHY binding properties.

Example:
	pcie_phy: phy@66038000 {
		compatible = "socionext,uniphier-ld20-pcie-phy";
		reg = <0x66038000 0x4000>;
		#phy-cells = <0>;
		clocks = <&sys_clk 24>;
		resets = <&sys_rst 24>;
		socionext,syscon = <&soc_glue>;
	};