allow policy to create a file by vfat (fs_type) for a case using sdcardfs

Change-Id: Ia938d73b1a49b9ba4acf906df37095d21edee22e
diff --git a/untrusted_app.te b/untrusted_app.te
index 8289dce..23c933b 100644
--- a/untrusted_app.te
+++ b/untrusted_app.te
@@ -151,6 +151,7 @@
   fs_type
   -fuse                     # sdcard
   -sdcardfs                 # sdcard
+  -vfat
   file_type
   -app_data_file            # The apps sandbox itself
   -media_rw_data_file       # Internal storage. Known that apps can