[media] via-camera: Add suspend/resume support

Add suspend/resume support to the via-camera driver, so that the video
continues streaming over a suspend-resume cycle.

Originally implemented by Jon Corbet.

[mchehab@redhat.com: fix a small CodingStyle issue]
Signed-off-by: Daniel Drake <dsd@laptop.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>