fix config file in Functional stage

Change-Id: I3e696a04d4f6e0206dc389edfd699e9b4a448460
diff --git a/jjb/pipeline/voltha-dt-physical-functional-tests.groovy b/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
index 26f0abc..98f4edb 100644
--- a/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
+++ b/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
@@ -77,7 +77,7 @@
 
     stage('Functional Tests') {
       environment {
-        ROBOT_CONFIG_FILE="$WORKSPACE/${configBaseDir}/${configDeploymentDir}/${configFileName}.yaml"
+        ROBOT_CONFIG_FILE="$WORKSPACE/${configBaseDir}/${configDeploymentDir}/${configFileName}-DT.yaml"
         ROBOT_FILE="Voltha_DT_PODTests.robot"
         ROBOT_LOGS_DIR="$WORKSPACE/RobotLogs/dt-workflow"
       }