staging: iio: tsl2583: remove unnecessary chip status check in taos_get_lux

taos_get_lux checks to see if the chip is in a working state. This
check is not necessary since it is only called from tsl2583_read_raw
and in_illuminance_calibrate_store (via taos_als_calibrate). The chip
state is already checked by these functions.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>