Monolithic Power Systems MP8867/MP8869 voltage regulator

Required properties:
- compatible: Must be one of the following.
	"mps,mp8867"
	"mps,mp8869"
- reg: I2C slave address.
- enable-gpios: enable gpios.
- mps,fb-voltage-divider: An array of two integers containing the resistor
  values R1 and R2 of the feedback voltage divider in kilo ohms.

Any property defined as part of the core regulator binding, defined in
./regulator.txt, can also be used.

Example:

	vcpu: regulator@62 {
		compatible = "mps,mp8869";
		regulator-name = "vcpu";
		regulator-min-microvolt = <700000>;
		regulator-max-microvolt = <850000>;
		regulator-always-on;
		regulator-boot-on;
		enable-gpios = <&porta 1 GPIO_ACTIVE_LOW>;
		mps,fb-voltage-divider = <80 240>;
		reg = <0x62>;
	};
