Update default revision to cm-12.1

Change-Id: I3bd785532952d0f355fcb941a0b4a36cd1642375
diff --git a/default.xml b/default.xml
index 3540b5d..565d20d 100644
--- a/default.xml
+++ b/default.xml
@@ -13,7 +13,7 @@
   <remote  name="private"
            fetch="ssh://git@github.com" />
 
-  <default revision="refs/heads/staging/cm-12.1"
+  <default revision="refs/heads/cm-12.1"
            remote="github"
            sync-c="true"
            sync-j="4" />