Documentation: tps65912: Add DT bindings for the TPS65912 PMIC

* TPS65912 Power Management Integrated Circuit bindings

Required properties:

 - compatible		: Should be "ti,tps65912".

 - reg			: Slave address or chip select number (I2C / SPI).

 - interrupt-parent	: The parent interrupt controller.

 - interrupts		: The interrupt line the device is connected to.

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

 - #interrupt-cells	: The number of cells to describe an IRQ, should be 2.

			    The first cell is the IRQ number.

			    The second cell is the flags, encoded as trigger

			    masks from ../interrupt-controller/interrupts.txt.

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

 - #gpio-cells		: Should be two.  The first cell is the pin number and

			    the second cell is used to specify flags.

			    See ../gpio/gpio.txt for more information.

 - regulators:		: List of child nodes that specify the regulator

			    initialization data. Child nodes must be named

			    after their hardware counterparts: dcdc[1-4] and

			    ldo[1-10]. Each child nodes is defined using the

			    standard binding for regulators.

Example:

	pmic: tps65912@2d {

		compatible = "ti,tps65912";

		reg = <0x2d>;

		interrupt-parent = <&gpio1>;

		interrupts = <28 IRQ_TYPE_LEVEL_LOW>;

		interrupt-controller;

		#interrupt-cells = <2>;

		gpio-controller;

		#gpio-cells = <2>;

		regulators {

			dcdc1 {

				regulator-name = "vdd_core";

				regulator-min-microvolt = <912000>;

				regulator-max-microvolt = <1144000>;

				regulator-boot-on;

				regulator-always-on;

			};

			ldo1 {

				regulator-name = "ldo1";

				regulator-min-microvolt = <1900000>;

				regulator-max-microvolt = <1900000>;

			};

		};

	};