coreinfo: Use SPDX license identifiers

- Remove copyright notices and add authors to AUTHORS
- Use SPDX license identifiers for all files
- Add coreinfo to the license header lint

Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Change-Id: Ib0c5328a4027849b1eda4f57141a898335230726
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45178
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

payloads/coreinfo/coreboot_module.c

@@ -1,16 +1,4 @@
-/*
- *
- * Copyright (C) 2008 Advanced Micro Devices, Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
+/* SPDX-License-Identifier: GPL-2.0-only */
 
 #include "coreinfo.h"
 #include <coreboot_tables.h>