[media] coda: do not use v4l2_dev in coda_timeout

The timeout delayed work might be scheduled even after the v4l2 device is
released.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>