iio: light: Add support for UPISEMI uS5182d als and proximity sensor

Add support for UPISEMI us5182d als and proximity sensor.
Supports raw readings.
Data sheet for this device can be found here:
http://www.upi-semi.com/temp/uS5182D-DS-P0103-temp.pdf



Signed-off-by: Adriana Reus <adriana.reus@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>