Fix bad substitution error

Change-Id: Ib6296ace3c448b3e465169fb6fc1fdf7a16f7282
diff --git a/jjb/pipeline/voltha-bbsim-tests.groovy b/jjb/pipeline/voltha-bbsim-tests.groovy
index 58fe4a8..df1f1a9 100644
--- a/jjb/pipeline/voltha-bbsim-tests.groovy
+++ b/jjb/pipeline/voltha-bbsim-tests.groovy
@@ -95,7 +95,7 @@
     stage('Deploy Voltha') {
       steps {
         sh '''
-           HELM_FLAG="${params.extraHelmFlags} "
+           HELM_FLAG="${extraHelmFlags} "
 
            if [ "${gerritProject}" = "voltha-go" ]; then
              HELM_FLAG+="-f $WORKSPACE/voltha/voltha-system-tests/tests/data/ci-test.yaml "