dt-bindings: mfd: Add DT bindings for max77650

MAX77650 ultra low-power PMIC from Maxim Integrated.

Required properties:

-------------------

- compatible:		Must be "maxim,max77650"

- reg:			I2C device address.

- interrupts:		The interrupt on the parent the controller is

			connected to.

- interrupt-controller: Marks the device node as an interrupt controller.

- #interrupt-cells:	Must be <2>.

- gpio-controller:	Marks the device node as a gpio controller.

- #gpio-cells:		Must be <2>. The first cell is the pin number and

			the second cell is used to specify the gpio active

			state.

Optional properties:

--------------------

gpio-line-names:	Single string containing the name of the GPIO line.

The GPIO-controller module is represented as part of the top-level PMIC

node. The device exposes a single GPIO line.

For device-tree bindings of other sub-modules (regulator, power supply,

LEDs and onkey) refer to the binding documents under the respective

sub-system directories.

For more details on GPIO bindings, please refer to the generic GPIO DT

binding document <devicetree/bindings/gpio/gpio.txt>.

Example:

--------

	pmic@48 {

		compatible = "maxim,max77650";

		reg = <0x48>;

		interrupt-controller;

		interrupt-parent = <&gpio2>;

		#interrupt-cells = <2>;

		interrupts = <3 IRQ_TYPE_LEVEL_LOW>;

		gpio-controller;

		#gpio-cells = <2>;

		gpio-line-names = "max77650-charger";

	};