iio: add bmp280 pressure and temperature driver

Minimal implementation, can read temperature and data using direct mode.

Datasheet available at
<http://ae-bst.resource.bosch.com/media/products/dokumente/bmp280/BST-BMP280-DS001-09.pdf>
Signed-off-by: Vlad Dogaru <vlad.dogaru@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/pressure/Kconfig

@@ -5,6 +5,17 @@
 
 menu "Pressure sensors"
 
+config BMP280
+	tristate "Bosch Sensortec BMP280 pressure sensor driver"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	 Say yes here to build support for Bosch Sensortec BMP280
+	 pressure and temperature sensor.
+
+	 To compile this driver as a module, choose M here: the module
+	 will be called bmp280.
+
 config HID_SENSOR_PRESS
 	depends on HID_SENSOR_HUB
 	select IIO_BUFFER

drivers/iio/pressure/Makefile

@@ -3,6 +3,7 @@
 #
 
 # When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_BMP280) += bmp280.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_MPL115) += mpl115.o
 obj-$(CONFIG_MPL3115) += mpl3115.o