[media] adv7604: debounce "format change" notifications

The bridge driver is only notified when the input status has changed
since the previous interrupt.

Signed-off-by: Mats Randgaard <matrandg@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>