MPS MP8865 Regulator Driver

Required properties:
- compatible: "mps,mp8865"
- reg: I2C slave address
- regulators: List of regulators provided by this controller.
  The definition for each of these nodes is defined using the standard binding
  for regulators at Documentation/devicetree/bindings/regulator/regulator.txt.

example:
	mp8865: mp8865@68 {
		compatible = "mps,mp8865";
		reg = <0x68>;
		status = "okay";
		regulators {
			vdd_gpu: mp8865_dcdc1 {
				regulator-name = "vdd_gpu";
				regulator-min-microvolt = <712500>;
				regulator-max-microvolt = <1500000>;
				regulator-always-on;
				regulator-boot-on;
			};
		};
	};