Update gitreview for v2.11, merge with branch=voltha-2.11 by default

Change-Id: I1e46eb980e799c2f9500da0bc5016dd7b39879ea
diff --git a/.gitreview b/.gitreview
index 028de3f..4daef32 100644
--- a/.gitreview
+++ b/.gitreview
@@ -3,3 +3,4 @@
 port=29418
 project=mcast.git
 defaultremote=origin
+defaultbranch=voltha-2.11