Fixes the duplicate creation of service/endpoint for cinder v2.

Change-Id: Ice1166b3af5685b8dcbc83dcb0b021a7530aa4cd
Fixes: rhbz#1153354
Signed-off-by: Gael Chamoulaud <gchamoul@redhat.com>
(cherry picked from commit dfdb49126b9925fa9aa112642939be3ed54bc748)