Fix the following coccinelle reports:

drivers/media/pci/saa7164/saa7164-dvb.c:341:2-5:
WARNING: Use BUG_ON instead of if condition followed by BUG

drivers/media/pci/saa7164/saa7164-dvb.c:483:2-5:
WARNING: Use BUG_ON instead of if condition followed by BUG.

Found using - Coccinelle (http://coccinelle.lip6.fr)
Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>