[media] adv7842: restart STDI once if format is not found

The STDI block may measure wrong values, especially for lcvs and lcf.
If the driver can not find any valid timing, the STDI block is restarted
to measure the video timings again. The function will return an error,
but the restart of STDI will generate a new STDI interrupt and the format
detection process will restart.

Copied from adv7604.

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