[media] v4l2-ctrls: v4l2_ctrl_add_handler should add all refs

Currently v4l2_ctrl_add_handler adds only the controls that are owned
by the handler. This is wrong. Instead all controls, whether owned or
not, should be added.

This is also implied by the v4l2-controls.txt documentation and it is
clearly the right thing to do. The only reason this was never noticed
before is because we never did this. Only recent changes in ivtv made
this error visible because there a third handler layer was added (handler
A inherits from handler B which inherits from C, D and E). Without this
change handler A only sees the controls owned by handler B and the controls
from C, D and E are missing.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>