Synaptics touch controller

Required properties:

 - compatible	: should be "synaptics,rmi4"
 - 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.
 - synaptics,irq-gpio	: irq gpio
 - synaptics,reset-gpio	: reset gpio

Optional property:
 - vdd-supply		: Analog power supply needed to power device
 - vcc_i2c-supply		: Power source required to pull up i2c bus
 - synaptics,i2c-pull-up	: specify to indicate pull up is needed
 - synaptics,button-map		: virtual key code mappings to be used
 - synaptics,x-flip		: modify orientation of the x axis
 - synaptics,y-flip		: modify orientation of the y axis
 - synaptics,panel-x		: panel x dimension
 - synaptics,panel-y		: panel y dimension
 - synaptics,fw-image-name	: name of firmware .img file in /etc/firmware

Example:
	i2c@f9927000 { /* BLSP1 QUP5 */
		cell-index = <5>;
		compatible = "qcom,i2c-qup";
		#address-cells = <1>;
		#size-cells = <0>;
		reg-names = "qup_phys_addr";
		reg = <0xf9927000 0x1000>;
		interrupt-names = "qup_err_intr";
		interrupts = <0 99 0>;
		gpios = <&msmgpio 19 0>, /* SCL */
			<&msmgpio 18 0>; /* SDA */
		qcom,i2c-bus-freq = <100000>;
		qcom,i2c-src-freq = <19200000>;

		synaptics@20 {
			compatible = "synaptics,rmi4"
			reg = <0x20>;
			interrupt-parent = <&msmgpio>;
			interrupts = <17 0x2>;
			vdd-supply = <&pm8226_l19>;
			vcc_i2c-supply = <&pm8226_lvs1>;
			synaptics,reset-gpio = <&msmgpio 16 0x00>;
			synaptics,irq-gpio = <&msmgpio 17 0x00>;
			synaptics,button-map = [8B 66 9E];
			synaptics,i2c-pull-up;
		};
	};