updating default image tags to "voltha-2.1"

Change-Id: I9376d134f75b88dd3b65325ee6412d562953b101
diff --git a/jjb/pipeline/voltha-bbsim-tests.groovy b/jjb/pipeline/voltha-bbsim-tests.groovy
index 26a4a3d..93b51f8 100644
--- a/jjb/pipeline/voltha-bbsim-tests.groovy
+++ b/jjb/pipeline/voltha-bbsim-tests.groovy
@@ -92,7 +92,7 @@
     stage('Deploy Voltha') {
       steps {
         sh """
-           HELM_FLAG="--set defaults.image_tag=2.1.0 "
+           HELM_FLAG="--set defaults.image_tag=voltha-2.1 "
 
            if [ "${gerritProject}" = "voltha-go" ]; then
              HELM_FLAG+="-f $WORKSPACE/voltha-system-tests/tests/data/ci-test.yaml"