clocksource/drivers/orion: Convert to SPDX identifier

The license information clearly states GPL version 2 only. The extra text
which excludes warranties is an excerpt of the corresponding GPLv2 clause
11.

So the SPDX identifier covers it completely.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220510171254.780389240@linutronix.deSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/timer-orion.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Marvell Orion SoC timer handling.
  *
  * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
  *
- * 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.
- *
  * Timer 0 is used as free-running clocksource, while timer 1 is
  * used as clock_event_device.
  */