nilfs2: update comment on deactivate_super at nilfs_get_sb

deactivate_super was replaced with deactivate_locked_super, but the
comment of nilfs_get_sb remain unchanged.  This renews the comment.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/super.c

@@ -1106,7 +1106,7 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
 	put_nilfs(nilfs);
 	deactivate_locked_super(s);
 	/*
-	 * deactivate_super() invokes close_bdev_exclusive().
+	 * deactivate_locked_super() invokes close_bdev_exclusive().
 	 * We must finish all post-cleaning before this call;
 	 * put_nilfs() needs the block device.
 	 */