staging: iio: light: Adding driver for ISL29018 ALS

adding support for the ISL 29018 ambient light and proximity sensor.

Addressed comments from reviews by Jonathan Cameron and Joe Perches
  * Removed some excess dbg prints that only printed function name
  * Renamed some properties to make them more descriptive
  * Added a property to list available adc resolutions
  * Defined arrays for resolutions/ranges as static const
  * Change loops initialization to memset for extensibility.
    * used sizeof() instead of ARRAY_SIZE() to be safer
  * Added a property to list available adc ranges
  * Fixed warnings and property names.

Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/staging/iio/light/Kconfig b/drivers/staging/iio/light/Kconfig
index 3ddc478..36d8bbe 100644
--- a/drivers/staging/iio/light/Kconfig
+++ b/drivers/staging/iio/light/Kconfig
@@ -12,3 +12,15 @@
 
 	 This driver can also be built as a module.  If so, the module
 	 will be called tsl2563.
+
+config SENSORS_ISL29018
+        tristate "ISL 29018 light and proximity sensor"
+        depends on I2C
+        default n
+        help
+         If you say yes here you get support for ambient light sensing and
+         proximity infrared sensing from Intersil ISL29018.
+         This driver will provide the measurements of ambient light intensity
+         in lux, proximity infrared sensing and normal infrared sensing.
+         Data from sensor is accessible via sysfs.
+