Update gitreview to anchor commits on the v2.11 branch

Change-Id: I62a377f7bbadeabd4e2f45588edea0eaa4a38115
diff --git a/.gitreview b/.gitreview
index 07b3894..b742563 100755
--- a/.gitreview
+++ b/.gitreview
@@ -3,3 +3,4 @@
 port=29418
 project=voltha-protos.git
 defaultremote=origin
+defaultbranch=voltha-2.11