[media] ivtv: Fix AUDIO_(BILINGUAL_)CHANNEL_SELECT regression

When I converted ivtv to the new decoder API I introduced a regression in the
support of the old channel select API.

Thanks to Martin Dauskardt for reporting this.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>