input: touchscreen: Add Elan_Sparrow touchscreen support

Elan Ektf3xx series touch controller

   Required properties:

		- compatible				: Should be "elan,ekth3500"

		- reg				        : I2C slave address of the device.

		- interrupt-parent			: Parent of interrupt.

		- interrupts				: Configuration of touch panel controller interrupt GPIO.

		- elan,irq-gpio				: Interrupt gpio which is to provide interrupts to

										host, same as "interrupts" node.It will also contain

										active low or active high information

  Optional properties:

		- vdd-supply				: Power supply needed to power up the device, when use

										external regulator, do not add this property.

		- vccio-supply				: Power source required to power up i2c bus.

										Ekth3500 series can provide 1.8V from internal

										LDO, add this properties base on hardware design.

		- reset-gpio			    : Reset gpio to control the reset of chip.

  Example:

		i2c@f9923000{

			elan_ktf@10 {

				compatible = "elan,ekth3500";

				reg = <0x10>;

				vdd-supply = <&pm8110_l19>;

				vccio-supply = <&pm8110_l14>;

				reset-gpio = <&msmgpio 0 GPIO_ACTIVE_LOW>;

				interrupt-parent = <&msmgpio>;

				interrupts = <1 0x2>;

				elan,irq-gpio = <&tlmm 65 0x2008>;>

			};

		};

# Makefile for the Elan touchscreen drivers.

obj-$(CONFIG_TOUCHSCREEN_EKTF3XXX_CHIPSET)   	+= 	elan_cros_i2c.o