iio: accel: Add support for Freescale MMA7660FC

Minimal implementation of an IIO driver for the Freescale
MMA7660FC 3-axis accelerometer. Datasheet:
http://www.nxp.com/files/sensors/doc/data_sheet/MMA7660FC.pdf

Includes:
- ACPI support;
- read_raw for x,y,z axes;
- reading and setting the scale (range) parameter.
- power management

Signed-off-by: Constantin Musca <constantin.musca@intel.com>
Reviewed-by: Martin Klepplinger <martink@posteo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index e4a758c..1df6361 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -136,6 +136,16 @@
 	  To compile this driver as a module, choose M here: the module
 	  will be called mma7455_spi.
 
+config MMA7660
+	tristate "Freescale MMA7660FC 3-Axis Accelerometer Driver"
+	depends on I2C
+	help
+	  Say yes here to get support for the Freescale MMA7660FC 3-Axis
+	  accelerometer.
+
+	  Choosing M will build the driver as a module. If so, the module
+	  will be called mma7660.
+
 config MMA8452
 	tristate "Freescale MMA8452Q and similar Accelerometers Driver"
 	depends on I2C