TPS549b22 Voltage regulators

Required properties:
- compatible: Must be "ti,tps549b22"
- reg: I2C slave address

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

Example:
	tps549b22@1e {
		compatible = "ti,tps549b22";
		reg = <0x1e>;
		regulators {
			#address-cells = <1>;
			#size-cells = <0>;
			regulator@0 {
				reg = <0>;
				regulator-compatible = "tps549b22_dcdc";
				regulator-name = "vdd_xxx";
				regulator-min-microvolt = <767500>;
				regulator-max-microvolt = <1535000>;
				regulator-always-on;
				regulator-boot-on;
			};
		};
	};