devicetree: Add documentation for UPISEMI us5182d ALS and Proximity sensor

Added entries in i2c/vendor-prefixes for the us5182d als and proximity sensor.
Also added a documentation file for this sensor's properties.

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