ubifs: Set s_uuid in super block to support ima/evm uuid options

This is required to provide uuid based integrity functionality for:
ima_policy (fsuuid option) and the 'evmctl' command ('--uuid' option).

Co-developed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Co-developed-by: Juergen Borleis <jbe@pengutronix.de>
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/super.c

@@ -2232,6 +2232,8 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
 		goto out_umount;
 	}
 
+	import_uuid(&sb->s_uuid, c->uuid);
+
 	mutex_unlock(&c->umount_mutex);
 	return 0;