f2fs: add SPDX license identifiers

Remove the verbose license text from f2fs files and replace them with
SPDX tags.  This does not change the license of any of the code.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c
index cd82e1c..fa707cd 100644
--- a/fs/f2fs/acl.c
+++ b/fs/f2fs/acl.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * fs/f2fs/acl.c
  *
@@ -7,10 +8,6 @@
  * Portions of this code from linux/fs/ext2/acl.c
  *
  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 #include <linux/f2fs_fs.h>
 #include "f2fs.h"