iio: magnetometer: Add support for MEMSIC MMC35240 sensor

Minimal implementation for MMC35240 3-axis magnetometer
sensor. It provides processed readings and possiblity to change
the sampling frequency.

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index 9746a2a..dcadfc4 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -47,6 +47,17 @@
 	  Say yes here to build support for the HID SENSOR
 	  Magnetometer 3D.
 
+config MMC35240
+	tristate "MEMSIC MMC35240 3-axis magnetic sensor"
+	select REGMAP_I2C
+	depends on I2C
+	help
+	  Say yes here to build support for the MEMSIC MMC35240 3-axis
+	  magnetic sensor.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mmc35240.
+
 config IIO_ST_MAGN_3AXIS
 	tristate "STMicroelectronics magnetometers 3-Axis Driver"
 	depends on (I2C || SPI_MASTER) && SYSFS