iio: add driver for Freescale MMA9553

Add support for Freescale MMA9553L Intelligent Pedometer Platform.

The following functionalities are supported:
 - step counter (counts the number of steps using a HW register)
 - step detector (generates an iio event at every step the user takes)
 - activity recognition (rest, walking, jogging, running)
 - speed
 - calories
 - distance

To get accurate pedometer results, the user's height, weight and gender
need to be configured.

The specifications can be downloaded from:
http://www.freescale.com/files/sensors/doc/ref_manual/MMA955xLSWRM.pdf
http://www.freescale.com/files/sensors/doc/ref_manual/MMA9553LSWRM.pdf

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index c53047d..7c9a9a9 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -126,4 +126,14 @@
 	  To compile this driver as a module, choose M here: the module
 	  will be called mma9551.
 
+config MMA9553
+	tristate "Freescale MMA9553L Intelligent Pedometer Platform Driver"
+	depends on I2C
+	select MMA9551_CORE
+	help
+	  Say yes here to build support for the Freescale MMA9553L
+	  Intelligent Pedometer Platform Driver.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mma9553.
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