platform/x86: intel_bxtwc_tmu: Convert to use SPDX identifier

Reduce size of duplicated comments by switching to use SPDX identifier.

No functional change.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/intel_bxtwc_tmu.c

+// SPDX-License-Identifier: GPL-2.0
 /*
- * intel_bxtwc_tmu.c - Intel BXT Whiskey Cove PMIC TMU driver
+ * Intel BXT Whiskey Cove PMIC TMU driver
  *
  * Copyright (C) 2016 Intel Corporation. All rights reserved.
  *
  * This driver adds TMU (Time Management Unit) support for Intel BXT platform.
  * It enables the alarm wake-up functionality in the TMU unit of Whiskey Cove
  * PMIC.
- *
- * 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.
- *
- * 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.
- *
  */
 
 #include <linux/module.h>