Focaltech touch controller with SPI interface

Required properties:
 - compatible:	"focaltech,fts"
 - gpios: 	the reset and interrupt GPIO number
 - reg: 	SPI chipselect
 - interrupts:	An interrupt node describing the IRQ line the chip's

Example nodes:

&spi2 {
	/* ... */
	focaltech@0 {
		compatible = "focaltech,fts";
		reg = <0x0>;
		spi-max-frequency = <6000000>;
		interrupt-parent = <&ap_gpio>;
		interrupts = <144 0x2000>;
		focaltech,reset-gpio = <&ap_gpio 145 GPIO_ACTIVE_HIGH>;
		focaltech,irq-gpio = <&ap_gpio 144 GPIO_ACTIVE_HIGH>;
		focaltech,max-touch-number = <5>;
		focaltech,display-coords =  <0 0 720 1600>;
	};
	/* ... */
};
