sepolicy: More policy for sdcardfs

Change-Id: Iddc6f86bd1e4b9942139acf9b7e75279b3865b8a
diff --git a/sepolicy/system_server.te b/sepolicy/system_server.te
index 6aaf50c..39ee935 100644
--- a/sepolicy/system_server.te
+++ b/sepolicy/system_server.te
@@ -7,3 +7,5 @@
 allow system_server persist_property_file:file { create_file_perms unlink };
 
 allow system_server storage_stub_file:dir { getattr };
+
+allow system_server media_rw_data_file:dir r_dir_perms;