phy: phy-mtk-tphy: use SPDX license tag

Use SPDX-License-Identifier tag instead of the GPL license text

Signed-off-by: Chunfeng Yun <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

drivers/phy/mediatek/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for the phy drivers.
 #

drivers/phy/mediatek/phy-mtk-tphy.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2015 MediaTek Inc.
  * Author: Chunfeng Yun <[e-mail]>
- *
- * This software is licensed under the terms of the GNU General Public
- * License version 2, as published by the Free Software Foundation, and
- * may be copied, distributed, and modified under those terms.
- *
- * 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.
  *
  */