Fixed directory failure in software upgrade 2.7 jobs

Change-Id: I9c169c6e98f1104371b6e276fff7a9baa802fa82
diff --git a/jjb/pipeline/voltha/master/software-upgrades.groovy b/jjb/pipeline/voltha/master/software-upgrades.groovy
index 917c078..fe4d81c 100644
--- a/jjb/pipeline/voltha/master/software-upgrades.groovy
+++ b/jjb/pipeline/voltha/master/software-upgrades.groovy
@@ -190,6 +190,7 @@
     stage('Install latest voltctl') {
       steps {
         sh """
+          mkdir -p $WORKSPACE/bin || true
           # install voltctl
           HOSTOS="\$(uname -s | tr "[:upper:]" "[:lower:"])"
           HOSTARCH="\$(uname -m | tr "[:upper:]" "[:lower:"])"