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/Makefile b/drivers/iio/accel/Makefile
index 71b6794..ba1165f 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -15,6 +15,8 @@
 obj-$(CONFIG_MMA7455_I2C)	+= mma7455_i2c.o
 obj-$(CONFIG_MMA7455_SPI)	+= mma7455_spi.o
 
+obj-$(CONFIG_MMA7660)	+= mma7660.o
+
 obj-$(CONFIG_MMA8452)	+= mma8452.o
 
 obj-$(CONFIG_MMA9551_CORE)	+= mma9551_core.o