Documentation: Document Hisilicon hix5hd2 sata PHY

Hisilicon hix5hd2 SATA PHY

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Required properties:

- compatible: should be "hisilicon,hix5hd2-sata-phy"

- reg: offset and length of the PHY registers

- #phy-cells: must be 0

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

Optional Properties:

- hisilicon,peripheral-syscon: phandle of syscon used to control peripheral.

- hisilicon,power-reg: offset and bit number within peripheral-syscon,

	register of controlling sata power supply.

Example:

	sata_phy: phy@f9900000 {

		compatible = "hisilicon,hix5hd2-sata-phy";

		reg = <0xf9900000 0x10000>;

		#phy-cells = <0>;

		hisilicon,peripheral-syscon = <&peripheral_ctrl>;

		hisilicon,power-reg = <0x8 10>;

	};