staging: iio: tsl2x7x: correct alignment of parenthesis

Correct error from checkpatch.pl to improve code readibility: Alignment
should match open parenthesis. This involved shortening the name of
tsl2x7x_als_gainadj and tsl2x7x_prx_gainadj to tsl2x7x_als_gain and
tsl2x7x_prx_gain respectively. This also required removing the
ch0lux and ch1lux local variables in order to get the line short
enough.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>