iio: mma8452: add support for MMA8652FC and MMA8653FC

MMA8652FC and MMA8653FC don't provide the transient interrupt source, so
the motion interrupt source is used by providing a new iio_chan_spec
definition, so that other supported devices are not affected by this.

Datasheets for the newly supported devices are available at Freescale's
website:

http://cache.freescale.com/files/sensors/doc/data_sheet/MMA8652FC.pdf
http://cache.freescale.com/files/sensors/doc/data_sheet/MMA8653FC.pdf

Signed-off-by: Martin Kepplinger <martin.kepplinger@theobroma-systems.com>
Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index fc53c29..8172ae5 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -106,7 +106,7 @@
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes here to build support for the following Freescale 3-axis
-	  accelerometers: MMA8452Q, MMA8453Q.
+	  accelerometers: MMA8452Q, MMA8453Q, MMA8652FC, MMA8653FC.
 
 	  To compile this driver as a module, choose M here: the module
 	  will be called mma8452.