iio: st-accel: add support for lis2dh12

This commit add support for STMicroelectronics lis2dh12 accelerometer.
Datasheet for this device can be found here:

http://www.st.com/st-web-ui/static/active/en/resource/technical/
document/datasheet/DM00091513.pdf

Signed-off-by: Giuseppe Barba <[e-mail]>
Acked-by: Denis Ciocca <[e-mail]>
Acked-by: Daniel Baluta <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/devicetree/bindings/iio/st-sensors.txt

···
 - st,lsm303dlm-accel
 - st,lsm330-accel
 - st,lsm303agr-accel
+- st,lis2dh12-accel
 
 Gyroscopes:
 - st,l3g4200d-gyro

drivers/iio/accel/Kconfig

···
 	help
 	  Say yes here to build support for STMicroelectronics accelerometers:
 	  LSM303DLH, LSM303DLHC, LIS3DH, LSM330D, LSM330DL, LSM330DLC,
-	  LIS331DLH, LSM303DL, LSM303DLM, LSM330.
+	  LIS331DLH, LSM303DL, LSM303DLM, LSM330, LIS2DH12.
 
 	  This driver can also be built as a module. If so, these modules
 	  will be created:

drivers/iio/accel/st_accel.h

···
 #define LSM303DLM_ACCEL_DEV_NAME	"lsm303dlm_accel"
 #define LSM330_ACCEL_DEV_NAME		"lsm330_accel"
 #define LSM303AGR_ACCEL_DEV_NAME	"lsm303agr_accel"
+#define LIS2DH12_ACCEL_DEV_NAME		"lis2dh12_accel"
 
 /**
 * struct st_sensors_platform_data - default accel platform data

drivers/iio/accel/st_accel_core.c

···
 			[3] = LSM330DL_ACCEL_DEV_NAME,
 			[4] = LSM330DLC_ACCEL_DEV_NAME,
 			[5] = LSM303AGR_ACCEL_DEV_NAME,
+			[6] = LIS2DH12_ACCEL_DEV_NAME,
 		},
 		.ch = (struct iio_chan_spec *)st_accel_12bit_channels,
 		.odr = {

drivers/iio/accel/st_accel_i2c.c

···
 		.compatible = "st,lsm303agr-accel",
 		.data = LSM303AGR_ACCEL_DEV_NAME,
 	},
+	{
+		.compatible = "st,lis2dh12-accel",
+		.data = LIS2DH12_ACCEL_DEV_NAME,
+	},
 	{},
 };
 MODULE_DEVICE_TABLE(of, st_accel_of_match);
···
 	{ LSM303DLM_ACCEL_DEV_NAME },
 	{ LSM330_ACCEL_DEV_NAME },
 	{ LSM303AGR_ACCEL_DEV_NAME },
+	{ LIS2DH12_ACCEL_DEV_NAME },
 	{},
 };
 MODULE_DEVICE_TABLE(i2c, st_accel_id_table);

drivers/iio/accel/st_accel_spi.c

···
 	{ LSM303DLM_ACCEL_DEV_NAME },
 	{ LSM330_ACCEL_DEV_NAME },
 	{ LSM303AGR_ACCEL_DEV_NAME },
+	{ LIS2DH12_ACCEL_DEV_NAME },
 	{},
 };
 MODULE_DEVICE_TABLE(spi, st_accel_id_table);