manifest: update for r33

Change-Id: Icda8f72b2da7c68fa3297ff995b04887a82aa8ff
diff --git a/default.xml b/default.xml
index 384e8b2..4e3beff 100644
--- a/default.xml
+++ b/default.xml
@@ -47,7 +47,7 @@
   <remote  name="private"
            fetch="ssh://git@github.com" />
 
-  <default revision="refs/tags/android-5.1.1_r26"
+  <default revision="refs/tags/android-5.1.1_r33"
            remote="aosp"
            sync-c="true"
            sync-j="8" />