trivial: media/video/cx88: add __init/__exit macros to cx88 drivers

Trivial patch which adds the __init and __exit macros to the module_init /
module_exit functions to several files in drivers/media/video/cx88/

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>