TPS51632 Voltage regulators

Required properties:
- compatible: Must be "ti,tps51632"
- reg: I2C slave address

Optional properties:
- ti,enable-pwm-dvfs: Enable the DVFS voltage control through the PWM interface.
- ti,dvfs-step-20mV: The 20mV step voltage when PWM DVFS enabled. Missing this
	will set 10mV step voltage in PWM DVFS mode. In normal mode, the voltage
	step is 10mV as per datasheet.

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

Example:

	tps51632 {
		compatible = "ti,tps51632";
		reg =  <0x43>;
		regulator-name = "tps51632-vout";
		regulator-min-microvolt = <500000>;
		regulator-max-microvolt = <1500000>;
		regulator-boot-on;
		ti,enable-pwm-dvfs;
		ti,dvfs-step-20mV;
	};
