set correct package name for BackupAgent

Bug: 157988888
Test: Manual
Change-Id: Ia05f362f3f5b166a573f80b859a227ad87f9e4e4
(cherry picked from commit cf30837d65902c9a5178660d59e95824a4b7ddd4)
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index dd4d7ca..9fe4c5e 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -43,7 +43,7 @@
     <application android:name="com.android.cellbroadcastreceiver.CellBroadcastReceiverApp"
             android:label="@string/app_label"
             android:icon="@mipmap/ic_launcher_cell_broadcast"
-            android:backupAgent="CellBroadcastBackupAgent"
+            android:backupAgent="com.android.cellbroadcastreceiver.CellBroadcastBackupAgent"
             android:defaultToDeviceProtectedStorage="true"
             android:supportsRtl="true"
             android:directBootAware="true">