manifest: android-7.1.1_r9 -> android-7.1.1_r21

Change-Id: Iacd564d829b05de3bcf1fa070535aab2ae230009
diff --git a/default.xml b/default.xml
index dc39be9..5440249 100644
--- a/default.xml
+++ b/default.xml
@@ -11,7 +11,7 @@
   <remote  name="aosp"
            fetch="https://android.googlesource.com"
            review="android-review.googlesource.com"
-           revision="refs/tags/android-7.1.1_r9" />
+           revision="refs/tags/android-7.1.1_r21" />
 
   <default revision="refs/heads/cm-14.1"
            remote="github"