Bosch BMP18x-series altimeter driver

Required properties:

 - compatible			: Should be "bosch,bmp180".
 - reg					: i2c slave address of the device.
 - vdd-supply		: Analog power supply needed to power device.
 - vddio-supply		: Digital IO power supply needed for IO and I2C.
 - bosch,chip-id		: Chip id for the bmp18x altimeter sensor.
 - bosch,oversample	: Sensor default oversampling value.
				Default oversampling value to be used at startup.
				Value range is 0-3 with rising sensitivity.
 - bosch,period	: Temperature measurement period (milliseconds).
				Set to zero if unsure.

Optional properties:

 - bosch,sw-oversample	: Boolean to enable software oversampling if
				this property is defined. Only take effect when
				default_oversampling is 3.

Example:
	i2c@f9925000 {
		bmp180@77 {
			status = "okay";
			reg = <0x77>;
			compatible = "bosch,bmp180";
			vdd-supply = <&pm8110_l19>;
			vddio-supply = <&pm8110_l14>;
			bosch,chip-id = <0x55>;
			bosch,oversample = <3>;
			bosch,period = <1000>;
			bosch,sw-oversample;
		};
	};