Texas Instruments TWL family (twl4030) reset and power management module

The power management module inside the TWL family provides several facilities
to control the power resources, including power scripts. For now, the
binding only supports the complete shutdown of the system after poweroff.

Required properties:
- compatible : must be one of the following
	"ti,twl4030-power"
	"ti,twl4030-power-reset"
	"ti,twl4030-power-idle"
	"ti,twl4030-power-idle-osc-off"

The use of ti,twl4030-power-reset is recommended at least on
3530 that needs a special configuration for warm reset to work.

When using ti,twl4030-power-idle, the TI recommended configuration
for idle modes is loaded to the tlw4030 PMIC.

When using ti,twl4030-power-idle-osc-off, the TI recommended
configuration is used with the external oscillator being shut
down during off-idle. Note that this does not work on all boards
depending on how the external oscillator is wired.

Optional properties:
- ti,use_poweroff: With this flag, the chip will initiates an ACTIVE-to-OFF or
		   SLEEP-to-OFF transition when the system poweroffs.

Example:
&i2c1 {
	clock-frequency = <2600000>;

	twl: twl@48 {
		reg = <0x48>;
		interrupts = <7>; /* SYS_NIRQ cascaded to intc */
		interrupt-parent = <&intc>;

		twl_power: power {
			compatible = "ti,twl4030-power";
			ti,use_poweroff;
		};
	};
};