FocalTech touch controller

The focaltech controller is connected to host processor
via i2c. The controller generates interrupts when the
user touches the panel. The host controller is expected
to read the touch coordinates over i2c and pass the coordinates
to the rest of the system.

Required properties:

 - compatible		: should be "focaltech,5x06"
 - reg			: i2c slave address of the device
 - interrupt-parent	: parent of interrupt
 - interrupts		: touch sample interrupt to indicate presense or release
				of fingers on the panel.
 - vdd-supply		: Power supply needed to power up the device
 - vcc_i2c-supply	: Power source required to power up i2c bus
 - focaltech,family-id	: family identification of the controller
 - focaltech,irq-gpio	: irq gpio which is to provide interrupts to host,
				same as "interrupts" node. It will also
				contain active low or active high information.
 - focaltech,reset-gpio	: reset gpio to control the reset of chip
 - focaltech,display-coords : display coordinates in pixels. It is a four
				tuple consisting of min x, min y, max x and
				max y values

Optional properties:

 - focaltech,panel-coords : panel coordinates for the chip in pixels.
				It is a four tuple consisting of min x,
				min y, max x and max y values
 - focaltech,i2c-pull-up : to specify pull up is required
 - focaltech,no-force-update : to specify force update is allowed
 - focaltech,button-map : button map of key codes. The number
				of key codes depend on panel

Example:
	i2c@f9924000 {
		ft5x06_ts@38 {
			compatible = "focaltech,5x06";
			reg = <0x38>;
			interrupt-parent = <&msmgpio>;
			interrupts = <61 0x2>;
			vdd-supply = <&pm8941_l22>;
			vcc_i2c-supply = <&pm8941_s3>;
			focaltech,reset-gpio = <&msmgpio 60 0x00>;
			focaltech,irq-gpio = <&msmgpio 61 0x00>;
			focaltech,panel-coords = <0 0 480 800>;
			focaltech,display-coords = <0 0 480 800>;
			focaltech,button-map= <158 102 139 217>;
			focaltech,family-id = <0x0a>;
		};
	};