CORD-1363 fix vrouter delete

Change-Id: I92eb35c29fc6d35cb2b4caa97d402b5b4d859b1b
(cherry picked from commit 775c5de510db341daec3a1a9bc582faa77ca2ef6)
diff --git a/xos/attic/vroutertenant_model.py b/xos/attic/vroutertenant_model.py
index 7fde19d..394f4a5 100644
--- a/xos/attic/vroutertenant_model.py
+++ b/xos/attic/vroutertenant_model.py
@@ -29,7 +29,7 @@
     if self.address_pool:
         ap = self.address_pool
         if ap:
-            ap[0].put_address(self.public_ip)
+            ap.put_address(self.public_ip)
             self.public_ip = None
 
 def delete(self, *args, **kwargs):