Max8925 Voltage regulators

max8925 regulator device register is still handled by mfd_add_devices, not by
of_xxx, so, it is not necessary to add compatible name. Also, those reg
offset and id info is stored in mfd_cell(see max8925-core.c), as a result
there is not private properties in dts.

node's name should match with the definition in max8925_regulator_matches
(see max8925-regulator.c)


Optional properties:
- Any optional property defined in bindings/regulator/regulator.txt


Example:


	regulators {
		SDV1 {
			regulator-min-microvolt = <637500>;
			regulator-max-microvolt = <1425000>;
			regulator-boot-on;
			regulator-always-on;
		};

		...
		...
	}