Add 'datasource: influxdb' to Grafana meta

Change-Id: Ib99e08a141ee821935561aabd5525ce90dfbf28d
diff --git a/keystone/meta/grafana.yml b/keystone/meta/grafana.yml
index 0ea6f4b..75c3ee7 100644
--- a/keystone/meta/grafana.yml
+++ b/keystone/meta/grafana.yml
@@ -8,6 +8,7 @@
     format: json
     template: keystone/files/grafana_dashboards/keystone_influxdb.json
   main:
+    datasource: influxdb
     row:
       ost-control-plane:
         title: OpenStack Control Plane
@@ -23,6 +24,7 @@
                 rawQuery: true
                 query: SELECT last(value) FROM cluster_status WHERE cluster_name = 'keystone' AND environment_label = '$environment' AND $timeFilter GROUP BY time($interval) fill(null)
   service_level:
+    datasource: influxdb
     row:
       keystone-service-level:
         title: Keystone Service Levels