[media] stk1160: remove V4L2_CHIP_MATCH_AC97 placeholder

It was just a placeholder and we want to get rid of the AC97 matching
define.
Also replace MATCH_HOST with MATCH_BRIDGE since we are here anyway.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>