No controls were reported, even though the ov7670 does have controls.

Two reasons for this: the v4l2_ctrl_handler_init() call must come
before the ov7670 is loaded (otherwise the ov7670 won't know that
its controls should be added to the bridge driver), and the
v4l2_ctrl_handler_free() call at the end should only be called if
the ret value is non-zero (otherwise you would just free all the
controls that were just added).
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>