Handle firewall_driver option

Change-Id: I90b7c5807ecd0ea8789e17a2fd701084982d39d3
Closes-Bug: PROD-20881
diff --git a/tests/pillar/gateway_legacy.sls b/tests/pillar/gateway_legacy.sls
index 6ce2ba0..c67c80b 100644
--- a/tests/pillar/gateway_legacy.sls
+++ b/tests/pillar/gateway_legacy.sls
@@ -2,6 +2,7 @@
   gateway:
     agent_mode: legacy
     dhcp_lease_duration: 86400
+    firewall_driver: noop
     backend:
       engine: ml2
       tenant_network_types: "flat,vxlan"