[media] ivtv: fix incorrect audio mode report in log_status

The log_status ioctl should report if the audio input has mode Bilingual. However, the
check against the itv->dualwatch_stereo_mode is completely wrong and is a left-over from
the distant past. Not only is the bitmask obviously wrong, the test itself is broken too
since itv->dualwatch_stereo_mode is no longer a bitmask at all.

Fix this code properly.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>