platform/x86: topstar-laptop: replace licence text with SPDX tag

Replace verbatim GPLv2 license copy with SPDX identifier.
Signed-off-by: Guillaume Douézan-Grard <gdouezangrard@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/topstar-laptop.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Topstar Laptop ACPI Extras driver
  *
@@ -6,10 +7,6 @@
  *
  * Implementation inspired by existing x86 platform drivers, in special
  * asus/eepc/fujitsu-laptop, thanks to their authors.
- *
- * 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.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt