Zeitec ZET6223 I2C touchscreen controller

Required properties:
- compatible		  : "zeitec,zet6223"
- reg			  : I2C slave address of the chip (0x76)
- interrupt-parent	  : a phandle pointing to the interrupt controller
			    serving the interrupt for this chip
- interrupts		  : interrupt specification for the zet6223 interrupt

Optional properties:

- vio-supply		  : Specification for VIO supply (1.8V or 3.3V,
			    depending on system interface needs).
- vcc-supply		  : Specification for 3.3V VCC supply.
- touchscreen-size-x	  : See touchscreen.txt
- touchscreen-size-y	  : See touchscreen.txt
- touchscreen-inverted-x  : See touchscreen.txt
- touchscreen-inverted-y  : See touchscreen.txt
- touchscreen-swapped-x-y : See touchscreen.txt

Example:

i2c@00000000 {

	zet6223: touchscreen@76 {
		compatible = "zeitec,zet6223";
		reg = <0x76>;
		interrupt-parent = <&pio>;
		interrupts = <6 11 IRQ_TYPE_EDGE_FALLING>
	};

};