Fix bug 1742 to update helm repo before installing metallb

Change-Id: I6cf974478d173f786f5a601fabc2877023ad82e7
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/installers/full_install_osm.sh b/installers/full_install_osm.sh
index b43ff7d..b232b4c 100755
--- a/installers/full_install_osm.sh
+++ b/installers/full_install_osm.sh
@@ -879,6 +879,7 @@
      addresses:
      - $METALLB_IP_RANGE" | sudo tee -a $OSM_DOCKER_WORK_DIR/metallb-config.yaml
     helm repo add metallb https://metallb.github.io/metallb
+    helm repo update
     helm install --create-namespace --namespace metallb-system metallb metallb/metallb -f $OSM_DOCKER_WORK_DIR/metallb-config.yaml
 }