[media] v4l2-dev: remove V4L2_FL_LOCK_ALL_FOPS

All drivers that needed V4L2_FL_LOCK_ALL_FOPS have been converted,
so remove this flag altogether.

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