MAX77838 regulators

Required properties:
- compatible: "maxim,max77838"
- reg: I2C slave address
- regulators: A node that houses a sub-node for each regulator within the
  device. Each sub-node is identified using the node's name, with valid
  values listed below. The content of each sub-node is defined by the
  standard binding for regulators; see regulator.txt.
  LDO[1-4] and BUCK respectively.

Optional properties:
- buck-ramp-up : buck ramp-up slew rate control.
					0 : 6.25mV/us
					1 : 12.5mV/us
					2 : 25mV/us
					3 : 50mV/us
- buck-ramp-down : buck ramp-down slew rate control.
					0 : 3.125mV/us
					1 : 6.25mV/us
					2 : 12.5mV/us
					3 : 25mV/us
- buck-fpwm : buck forced PWM.
				0 : Disable
				1 : Enable
- buck-fsrad : buck falling slew rate active discharge
				0 : Disable
				1 : Enable
- uvlo-fall-threshold : Vsys UVLO falling threshold
						0 : 2.30V
						1 : 2.35V
						2 : 2.40V
						3 : 2.45V

- active-discharge-enable : All regulators have active discharge enable setting
							0 : Disable
							1 : Enable

Each regulator is defined using the standard binding for regulators.

Example:

	max77838@60 {
		compatible = "maxim,max77838";
		reg = <0x60>;

		regulators {
			LDO1 {
				regulator-min-microvolt = <600000>;
				regulator-max-microvolt = <3775000>;
				active-discharge-enable = <1>;
			};
			
			LDO2 {
				active-discharge-enable = <1>;
			};

			...

			LDO4 {
				active-discharge-enable = <1>;
			};

			BUCK {
				regulator-boot-on;
				regulator-always-on;
			};
		};
		buck-ramp-up = <0>; 	/* 6.25mV/us */
		buck-fpwm = <0>;		/* Disable */
		
		uvlo-fall-threshold = <1>;	/* 2.35V */
	};
