staging: iio: tsl2x7x: remove unnecessary parentheses

This patch fixes the error 'Unnecessary parentheses around 'XXX' from
checkpatch.pl. It also fixes several other places with unnecessary
parentheses that checkpatch.pl did not detect.

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