media: pci: saa7164-vbi.c: replace if (cond) BUG() with BUG_ON()

Fix the following coccinelle reports:

drivers/media/pci/saa7164/saa7164-vbi.c:707:2-5:
WARNING: Use BUG_ON instead of if condition followed by BUG.

drivers/media/pci/saa7164/saa7164-vbi.c:760:2-5:
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>