clocksource/drivers/bcm_kona: Convert to SPDX identifier

The license information clearly states GPL version 2 only. The extra text
which excludes warranties is a transcript of the corresponding GPLv2 clause
11, which is explicitely referenced for details.

So the SPDX identifier covers it completely.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Broadcom Kernel Team <bcm-kernel-feedback-list@broadcom.com>
Cc: linux-spdx@vger.kernel.org
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220510171254.404209482@linutronix.de
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Author: KAGA-KOKO

drivers/clocksource/bcm_kona_timer.c

@@ -1,15 +1,5 @@
-/*
- * Copyright (C) 2012 Broadcom Corporation
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation version 2.
- *
- * This program is distributed "as is" WITHOUT ANY WARRANTY of any
- * kind, whether express or implied; without even the implied warranty
- * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2012 Broadcom Corporation
 
 #include <linux/init.h>
 #include <linux/irq.h>