[media] cx88: remove return after BUG()

As reported by smatch:

drivers/media/pci/cx88/cx88-video.c:699 get_queue() info: ignoring unreachable code.
drivers/media/pci/cx88/cx88-video.c:714 get_resource() info: ignoring unreachable code.
drivers/media/pci/cx88/cx88-video.c:815 video_read() info: ignoring unreachable code.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>