HiSilicon STB PCIE/SATA/USB3 PHY

Required properties:
- compatible: Should be "hisilicon,hi3798cv200-combphy"
- reg: Should be the address space for COMBPHY configuration and state
  registers in peripheral controller, e.g. PERI_COMBPHY0_CFG and
  PERI_COMBPHY0_STATE for COMBPHY0 Hi3798CV200 SoC.
- #phy-cells: Should be 1.  The cell number is used to select the phy mode
  as defined in <dt-bindings/phy/phy.h>.
- clocks: The phandle to clock provider and clock specifier pair.
- resets: The phandle to reset controller and reset specifier pair.

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

Optional properties:
- hisilicon,fixed-mode: If the phy device doesn't support mode select
  but a fixed mode setting, the property should be present to specify
  the particular mode.
- hisilicon,mode-select-bits: If the phy device support mode select,
  this property should be present to specify the register bits in
  peripheral controller, as a 3 integers tuple:
  <register_offset bit_shift bit_mask>.

Notes:
- Between hisilicon,fixed-mode and hisilicon,mode-select-bits, one and only
  one of them should be present.
- The device node should be a child of peripheral controller that contains
  COMBPHY configuration/state and PERI_CTRL register used to select PHY mode.
  Refer to arm/hisilicon/hisilicon.txt for the parent peripheral controller
  bindings.

Examples:

perictrl: peripheral-controller@8a20000 {
	compatible = "hisilicon,hi3798cv200-perictrl", "syscon",
		     "simple-mfd";
	reg = <0x8a20000 0x1000>;
	#address-cells = <1>;
	#size-cells = <1>;
	ranges = <0x0 0x8a20000 0x1000>;

	combphy0: phy@850 {
		compatible = "hisilicon,hi3798cv200-combphy";
		reg = <0x850 0x8>;
		#phy-cells = <1>;
		clocks = <&crg HISTB_COMBPHY0_CLK>;
		resets = <&crg 0x188 4>;
		hisilicon,fixed-mode = <PHY_TYPE_USB3>;
	};

	combphy1: phy@858 {
		compatible = "hisilicon,hi3798cv200-combphy";
		reg = <0x858 0x8>;
		#phy-cells = <1>;
		clocks = <&crg HISTB_COMBPHY1_CLK>;
		resets = <&crg 0x188 12>;
		hisilicon,mode-select-bits = <0x0008 11 (0x3 << 11)>;
	};
};
