Binding for Realtek rtp590x Driver

Required properties:
- compatible: "realtek,rtp5901" or "realtek,rtp5903"
- reg: I2C slave address

Optional properties:
- regulator-microvolt: default voltage
- regulator-virt-consumer: virtual consumer

  Sub nodes for regulator_init_data
    rtp5901 has maximum 9 nodes. (label name: ldo1_reg ~ ldo5_reg and dcdc1_reg ~ dcdc4_reg)
    rtp5903 has maximum 6 nodes. (label name: ldo3_reg, ldo5_reg and dcdc1_reg ~ dcdc4_reg)
    For more details, please see the following binding document.
    (Documentation/devicetree/bindings/regulator/regulator.txt)

Example:

/include/ "rtp590x.dtsi"
&rtp590x{
	rtp590x: rtp5903@30 {
		compatible = "realtek,rtp5903";
		reg = <0x30>;
		status = "okay";

		regulators {

			ldo3_reg: regulator@2 {
				regulator-name= "LDO1";
				regulator-microvolt = <1800000>;
				regulator-min-microvolt = <1800000>;
				regulator-max-microvolt = <3300000>;
				regulator-virt-consumer;
				regulator-state-mem {
					regulator-off-in-suspend;
				};
				regulator-state-disk {
					regulator-off-in-suspend;
				};
			};
...
		};
	};
};
