Sensortek stk301x, stk321x and stk331x ambient light/proximity 3-in-1 sensor

Required properties:

 - compatible		: Should be "stk,stk3x1x".
 - reg					: i2c slave address of the device.
 - interrupt-parent	: Parent of interrupt.
 - interrupts		: Sensor will issue interrupt when preset condition is met,
				typically when proximity sensor detect a change on near/far state.
 - vdd-supply		: Main power supply to power sensor.
 - vio-supply		: Power supply required to pullup I2C bus.
 - stk,irq-gpio	: irq gpio which is to provide interrupts to host, same as
				"interrupts" node.
 - stk,transmittance : Transmittance rate of glass above the ambient light
				detection window. The value may not be equal to real transmittance
				but just a relative value.
 - stk,state-reg	: The default setting of state register.
 - stk,psctrl-reg	: The default setting for proximity sensor.
 - stk,alsctrl-reg	: The default setting for ambient light sensor.
 - stk,ledctrl-reg	: The default setting for IR LED.
 - stk,wait-reg	: The default setting for wait time.
 - stk,ps-thdh	: High threshold for proximity sensor, sensor will report
				"near" if the proximity sensor reading is larger or equal to this
				value.
 - stk,ps-thdl	: Low threshold for proximity sensor, sensor will report
				"far" if the proximity sensor reading is larger than this value.

Optional properties:

 - stk,use-fir	: Boolean to enable light data jitter suppressing FIR filter.

Example:
	i2c@f9925000 {
		stk@48 {
			compatible = "stk,stk3x1x";
			reg = <0x48>;
			interrupt-parent = <&msmgpio>;
			interrupts = <80 0x2>;
			vdd-supply = <&pm8110_l19>;
			vio-supply = <&pm8110_l14>;
			stk,irq-gpio = <&msmgpio 80 0x02>;
			stk,transmittance = <500>;
			stk,state-reg = <0x00>;
			stk,psctrl-reg = <0x71>;
			stk,alsctrl-reg = <0x38>;
			stk,ledctrl-reg = <0xFF>;
			stk,wait-reg = <0x07>;
			stk,ps-thdh = <1700>;
			stk,ps-thdl = <1500>;
			stk,use-fir;
		};