Increase timeout for DT tests for the nightly runs

Change-Id: I13915a8977a086ea1f994ad551910a9d3399442b
diff --git a/jjb/pipeline/voltha-dt-physical-functional-tests.groovy b/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
index c234f41..1ebd19d 100644
--- a/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
+++ b/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
@@ -23,7 +23,7 @@
     label "${params.buildNode}"
   }
   options {
-    timeout(time: 440, unit: 'MINUTES')
+    timeout(time: 640, unit: 'MINUTES')
   }
 
   environment {