Handle dhcp_lease_duration option

Change-Id: I3b1a6ba31c55dde7e3e02e1eb3c46dddee515816
Closes-Bug: PROD-20880
diff --git a/tests/pillar/gateway_legacy.sls b/tests/pillar/gateway_legacy.sls
index 66e99fa..6ce2ba0 100644
--- a/tests/pillar/gateway_legacy.sls
+++ b/tests/pillar/gateway_legacy.sls
@@ -1,6 +1,7 @@
 neutron:
   gateway:
     agent_mode: legacy
+    dhcp_lease_duration: 86400
     backend:
       engine: ml2
       tenant_network_types: "flat,vxlan"