staging: iio: tsl2x7x: correct alignment of parenthesis

Correct error from checkpatch.pl to improve code readibility: Alignment
should match open parenthesis. An unnecessary cast to 'struct
tsl2x7x_lux *' was removed and the return value of static definition of
in_illuminance0_calibscale_available_show() was put on its own line
due to the length of that sysfs attribute.

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