[media] marvell-cam: Remove broken "owner" logic

The marvell cam driver retained just enough of the owner-tracking logic
from cafe_ccic to be broken; it could, conceivably, cause the driver to
release DMA memory while the controller is still active.  Simply remove the
remaining pieces and ensure that the controller is stopped before we free
things.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>