staging: dgnc: Fix unnecessary space warning.

Fixed "Unnecessary space before function pointer argument" checkpatch.pl
warning in dgnc_driver.h

Signed-off-by: Gulsah Kose <gulsah.1004@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>