staging: iio: tsl2583: check return values from taos_chip_{on,off}

The return value from taos_chip_on() and taos_chip_off() was not
checked in taos_luxtable_store() and taos_probe(). This patch adds
proper error checking to these function calls.

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