* IQS253 proximity sensor

Required properties:
- compatible: must be "azoteq,iqs253"
- reg: i2c address of the device. It is one of 0x44-0x47.
- vendor: vendor of the hardware part.
- proximity,max-range: maximum range of this sensor's value in SI units.
- proximity,integration-time: minimum sampling period in nano seconds.
- proximity,power-consumed: rough estimate of this sensor's power consumption in mA.
- rdy-gpio: gpio to be used for i2c handshake with the sensor.
- wake-gpio: gpio to be used for wakeup on stylus insert/removal event.
- sar-gpio: gpio to be used for sending proximity event to SAR sensor.

Optional properties:
- stylus-detect: specify this option to enable stylus detection

Example:

	iqs253@44 {
		compatible = "azoteq,iqs253";
		reg = <0x44>;
		vendor = "Azoteq";
		proximity,max-range = "2"; /* 2 cm */;
		proximity,integration-time = "16000000"; /* 16 msec */
		proximity,power-consumed = "1.67"; /* mA */
		rdy-gpio = <&gpio TEGRA_GPIO(PK, 5) 1>;
		wake-gpio = <&gpio TEGRA_GPIO(PW, 3) 1>;
		sar-gpio = <&gpio TEGRA_GPIO(I, 2) 1>;
		stylus-detect;
	};
