[media] v4l2 core: remove the obsolete dv_preset support

These ioctls are no longer used by any drivers, so remove them.

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