[media] adv7511: fix VIC autodetect

The adv7511 will automatically fill in the VIC code in the AVI InfoFrame
based on the timings of the incoming pixelport signals.

However, to have this work correctly it needs to specify the fps
value in a register. After doing this the proper VIC code is filled in.

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