dm vdo funnel-queue: change from uds_ to vdo_ namespace

Also return VDO_SUCCESS from vdo_make_funnel_queue.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Chung Chung <cchung@redhat.com>
Signed-off-by: Matthew Sakai <msakai@redhat.com>