Sensirion SHT15 Humidity and Temperature Sensor

Required properties:

 - "compatible": must be "sensirion,sht15".
 - "data-gpios": GPIO connected to the data line.
 - "clk-gpios": GPIO connected to the clock line.
 - "vcc-supply": regulator that drives the VCC pin.

Example:

	sensor {
		pinctrl-names = "default";
		pinctrl-0 = <&pinctrl_sensor>;
		compatible = "sensirion,sht15";
		clk-gpios = <&gpio4 12 0>;
		data-gpios = <&gpio4 13 0>;
		vcc-supply = <&reg_sht15>;
	};