Refactored all pipelines branches to external soft param

Change-Id: I3e451815029227f287aa1575099b0cd25b72433d
diff --git a/jenkins/client/job/opencontrail/build/dpdk-extra.yml b/jenkins/client/job/opencontrail/build/dpdk-extra.yml
index 0a152f1..2d4e4d8 100644
--- a/jenkins/client/job/opencontrail/build/dpdk-extra.yml
+++ b/jenkins/client/job/opencontrail/build/dpdk-extra.yml
@@ -54,6 +54,7 @@
             scm:
               type: git
               url: "${_param:jenkins_gerrit_url}/mk/mk-pipelines"
+              branch: "${_param:jenkins_pipelines_branch}"
               credentials: "gerrit"
               script: build-extra-dpdk-pipeline.groovy
             quiet_period: 120