Cypress I2C Touchpad

Required properties:
- compatible: must be "cypress,cyapa".
- reg: I2C address of the chip.
- interrupt-parent: a phandle for the interrupt controller (see interrupt
	binding[0]).
- interrupts: interrupt to which the chip is connected (see interrupt
	binding[0]).

Optional properties:
- wakeup-source: touchpad can be used as a wakeup source.
- pinctrl-names: should be "default" (see pinctrl binding [1]).
- pinctrl-0: a phandle pointing to the pin settings for the device (see
	pinctrl binding [1]).
- vcc-supply: a phandle for the regulator supplying 3.3V power.

[0]: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
[1]: Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt

Example:
	&i2c0 {
		/* ... */

		/* Cypress Gen3 touchpad */
		touchpad@67 {
			compatible = "cypress,cyapa";
			reg = <0x67>;
			interrupt-parent = <&gpio>;
			interrupts = <2 IRQ_TYPE_EDGE_FALLING>;	/* GPIO 2 */
			wakeup-source;
		};

		/* Cypress Gen5 and later touchpad */
		touchpad@24 {
			compatible = "cypress,cyapa";
			reg = <0x24>;
			interrupt-parent = <&gpio>;
			interrupts = <2 IRQ_TYPE_EDGE_FALLING>;	/* GPIO 2 */
			wakeup-source;
		};

		/* ... */
	};
