iio: light: ltr501: Added ltr303 driver support

Previously ltr501 driver supported a number of light and,
proximity sensors including ltr501, ltr559 and ltr301.
This adds support for another light sensor ltr303
used in Seeed Studio reTerminal, a carrier board
for Raspberry Pi 4 CM.

Signed-off-by: Maslov Dmitry <maslovdmitry@seeed.cc>
Link: https://lore.kernel.org/r/20211106174137.6783-1-maslovdmitry@seeed.cc


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>