Update mongodb values in OSM helm chart to include fullnameOverride

Change-Id: Ifa8b65471f205beff313f213b50f1f98a5e3038b
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/installers/helm/osm/values.yaml b/installers/helm/osm/values.yaml
index a046b9a..5c9ea2c 100644
--- a/installers/helm/osm/values.yaml
+++ b/installers/helm/osm/values.yaml
@@ -337,6 +337,7 @@
 
 mongodb:
   enabled: true
+  fullnameOverride: "mongodb-k8s"
   replicaCount: 1
   service:
     nameOverride: "mongodb-k8s"