Point grafana DS to prometheus-relay

Add prometheus relay docker image address

Change-Id: Id1c7800c31b7e4f25684825ba14c91afc573da0c
diff --git a/classes/cluster/sl-os-ovs/stacklight/client.yml b/classes/cluster/sl-os-ovs/stacklight/client.yml
index ddc2f9f..fde267a 100644
--- a/classes/cluster/sl-os-ovs/stacklight/client.yml
+++ b/classes/cluster/sl-os-ovs/stacklight/client.yml
@@ -16,4 +16,4 @@
     grafana_user: admin
     grafana_password: ${_param:grafana_admin_password}
     grafana_prometheus_address: ${_param:stacklight_monitor_address}
-    grafana_prometheus_port: 15010
+    grafana_prometheus_port: 15016