clocksource/drivers/timer-meson6: Update with SPDX Licence identifier

Comply with the licensing rules defined in the documentation.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/timer-meson6.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Amlogic Meson6 SoCs timer handling.
  *
  * Copyright (C) 2014 Carlo Caione <carlo@caione.org>
  *
  * Based on code from Amlogic, Inc
- *
- * This file is licensed under the terms of the GNU General Public
- * License version 2.  This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
  */
 
 #include <linux/bitfield.h>