Add dhcp-networks agent function

Related-PROD: PROD-28687 (PROD:28687)

Change-Id: Ica9c2579f1620ea11ec6ef0b5f0931797ab5716a
diff --git a/openstack/networking/v2/extensions/agents/urls.go b/openstack/networking/v2/extensions/agents/urls.go
index e4fac8d..4336ab9 100644
--- a/openstack/networking/v2/extensions/agents/urls.go
+++ b/openstack/networking/v2/extensions/agents/urls.go
@@ -5,3 +5,7 @@
 func listURL(c *gophercloud.ServiceClient) string {
 	return c.ServiceURL("agents")
 }
+
+func listDHCPNetworksURL(client *gophercloud.ServiceClient, id string) string {
+	return client.ServiceURL("agents", id, "dhcp-networks")
+}