* Power controller for simple lcd panels

Some LCD panels provide a simple control interface for the host system. The
control mechanism would include a nRESET line connected to a gpio of the host
system and a Vcc supply line which the host can optionally be controlled using
a voltage regulator. Such simple panels do not support serial command
interface (such as i2c or spi) or memory-mapped-io interface.

Required properties:
- compatible: should be 'lcd-powercontrol'

- lcd-reset-gpio: The GPIO number of the host system used to control the
  nRESET line. The format of the gpio specifier depends on the gpio controller
  of the host system.

Optional properties:
- lcd-reset-active-high: When the nRESET line is asserted low, the lcd panel
  is reset and stays in reset mode as long as the nRESET line is asserted low.
  This is the default behaviour of most lcd panels. If a lcd panel requires the
  nRESET line to be asserted high for panel reset, then this property is used.
  Note: Some platforms might allow inverting the polarity of the gpio output
  in the 'lcd-reset-gpio' gpio specifier. On such platforms, if the polarity
  is used to control the output of the gpio, then this property should not be
  used.

- vcc-lcd-supply: phandle of the regulator that controls the vcc supply to
  the lcd panel.

Example:

	lcd_pwrctrl {
		compatible = "lcd-powercontrol";
		lcd-reset-gpio = <&gpe0 4 1 0 0>;
		lcd-reset-active-high;
		lcd-vcc-supply = <&regulator7>;
	};
