Update .gitreview default branch for v2.11

Change-Id: I0cff82700a088168e1680ddd2f09358fbbfe6b6b
diff --git a/.gitreview b/.gitreview
index b6f18ed..3f80cb1 100644
--- a/.gitreview
+++ b/.gitreview
@@ -3,4 +3,4 @@
 port=29418
 project=voltha-helm-charts.git
 defaultremote=origin
-defaultbranch=master
+defaultbranch=voltha-2.11