hrtimers/tick/clockevents: Remove sloppy license references

"For licencing details see kernel-base/COPYING" and similar license
references have no value over the SPDX identifier. Remove them.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: David Riley <davidriley@chromium.org>
Cc: Colin Cross <ccross@android.com>
Cc: Mark Brown <broonie@kernel.org>
Link: https://lkml.kernel.org/r/20181031182252.963632760@linutronix.de

kernel/time/tick-broadcast.c

@@ -6,9 +6,6 @@
  * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
  * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
  * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
- *
- * This code is licenced under the GPL version 2. For details see
- * kernel-base/COPYING.
  */
 #include <linux/cpu.h>
 #include <linux/err.h>