GPIO line that should be set high/low to power off a device

Required properties:
- compatible : should be "gpio-poweroff".
- gpios : The GPIO to set high/low, see "gpios property" in
  Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be
  low to power down the board set it to "Active Low", otherwise set
  gpio to "Active High".

Optional properties:
- input : Initially configure the GPIO line as an input. Only reconfigure
  it to an output when the pm_power_off function is called. If this optional
  property is not specified, the GPIO is initialized as an output in its
  inactive state.


Examples:

gpio-poweroff {
	compatible = "gpio-poweroff";
	gpios = <&gpio 4 0>; /* GPIO 4 Active Low */
};
