Touchscreen Virtual Keys Device

Generate virtual keys sysfs entry for Android

Required properties:

 - compatible	: should be "qcom,gen-vkeys"
 - label		: name of the touch controller
 - qcom,disp-maxx	: Maximum x-coordinate of display
 - qcom,disp-maxy	: Maximum y-coordinate of display
 - qcom,panel-maxx	: Maximum x-coordinate of touch panel
 - qcom,panel-maxy	: Maximum y-coordinate of touch panel
 - qcom,key-codes	: Array of key codes for virtual keys

Optional properties:
 - qcom,y-offset	: Offset of y-location for virtual keys, default 0

Example:
	gen-vkeys {
		compatible = "qcom,gen-vkeys";
		label = "atmel_mxt_ts";
		qcom,disp-maxx = <720>;
		qcom,disp-maxy = <1280>;
		qcom,panel-maxx = <760>;
		qcom,panel-maxy = <1424>;
		qcom,key-codes = <158 139 102 217>;
		qcom,y-offset = <35>;
	};