V4L/DVB: ivtv: Avoid accidental video standard change

For yuv video output, pass fake values to avoid firmware trying to change
video standard.

Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>