staging: iio: tsl2x7x: remove ch0 and ch1 variables from tsl2x7x_get_lux()

Remove the ch0 and ch1 variables from tsl2x7x_get_lux() and
write those values directly into the chip->als_cur_info.als_ch0
and chip->als_cur_info.als_ch01 variables.

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