Voltage/Current Regulators

Optional properties:
- regulator-name: A string used as a descriptive name for regulator outputs
- regulator-min-microvolt: smallest voltage consumers may set
- regulator-max-microvolt: largest voltage consumers may set
- regulator-microvolt-offset: Offset applied to voltages to compensate for voltage drops
- regulator-min-microamp: smallest current consumers may set
- regulator-max-microamp: largest current consumers may set
- regulator-always-on: boolean, regulator should never be disabled
- regulator-boot-on: bootloader/firmware enabled regulator
- <name>-supply: phandle to the parent supply/regulator node

Example:

	xyzreg: regulator@0 {
		regulator-min-microvolt = <1000000>;
		regulator-max-microvolt = <2500000>;
		regulator-always-on;
		vin-supply = <&vin>;
	};

Regulator Consumers:
Consumer nodes can reference one or more of its supplies/
regulators using the below bindings.

- <name>-supply: phandle to the regulator node

These are the same bindings that a regulator in the above
example used to reference its own supply, in which case
its just seen as a special case of a regulator being a
consumer itself.

Example of a consumer device node (mmc) referencing two
regulators (twl_reg1 and twl_reg2),

	twl_reg1: regulator@0 {
		...
		...
		...
	};

	twl_reg2: regulator@1 {
		...
		...
		...
	};

	mmc: mmc@0x0 {
		...
		...
		vmmc-supply = <&twl_reg1>;
		vmmcaux-supply = <&twl_reg2>;
	};
