VPNaaS datamodel IKEPolicy lifetime unit typo

There was a typo in handling the IKEPolicy
lifetime, during the IKEPolicy creation time.

-Fixed the typo issue

Fixes bug 1207572

Change-Id: If8c56619c9a340a04e336b6b83d219df10b91e6c

neutron/db/vpn/vpn_db.py

@@ -358,7 +358,7 @@ def create_ikepolicy(self, context, ikepolicy):
         ike = ikepolicy['ikepolicy']
         tenant_id = self._get_tenant_id_for_create(context, ike)
         lifetime_info = ike.get('lifetime', [])
-        lifetime_units = lifetime_info.get('unit', 'seconds')
+        lifetime_units = lifetime_info.get('units', 'seconds')
         lifetime_value = lifetime_info.get('value', 3600)
 
         with context.session.begin(subtransactions=True):