staging: iio: addac: adt7316.h Fix Unnecessary space after function pointer name

The patch fixes the following checkpatch.pl warnings:
WARNING: Unnecessary space after function pointer name.

Signed-off-by: Aybuke Ozdemir <aybuke.147@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>