sepolicy: Mark mkfs as system_file_type

Change-Id: I802fa29890ab867f152e8c3ee8e74c0823c88094
diff --git a/sepolicy/private/mkfs.te b/sepolicy/private/mkfs.te
index dbd97b8..2c16520 100644
--- a/sepolicy/private/mkfs.te
+++ b/sepolicy/private/mkfs.te
@@ -1,5 +1,5 @@
 type mkfs, coredomain, domain;
-type mkfs_exec, exec_type, file_type;
+type mkfs_exec, system_file_type, exec_type, file_type;
 
 init_daemon_domain(mkfs)