Use GERRIT_BRACH param in Jenkinsfile

Change-Id: I6ebaee1636bb99f0e2776489bc9222a9a87661e0
Signed-off-by: Wesley Hirsch <wesley.hirsch@riftio.com>
diff --git a/Jenkinsfile b/Jenkinsfile
index 85e99ab..a4a3fa3 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -11,7 +11,7 @@
 
 def devops_checkout() {
     dir('devops') {
-        git url: "${PROJECT_URL_PREFIX}/osm/devops"
+        git url: "${PROJECT_URL_PREFIX}/osm/devops", branch: params.GERRIT_BRANCH
     }
 }