Allow vold to mount at /mnt/user/.*

Bug: 111890351
Test: Device boots and no selinux denials when vold mounts
      at /mnt/user/.*

Change-Id: Id962a85af9f99c54421f0820a22880be36c2e478

public/vold.te

@@ -68,7 +68,7 @@ allow vold media_rw_data_file:file create_file_perms;
 allow vold { mnt_media_rw_stub_file storage_stub_file }:dir { mounton create rmdir getattr setattr };
 
 # Manage per-user primary symlinks
-allow vold mnt_user_file:dir create_dir_perms;
+allow vold mnt_user_file:dir { create_dir_perms mounton };
 allow vold mnt_user_file:lnk_file create_file_perms;
 
 # Allow to create and mount expanded storage