genirq: Cleanup top of file comments

Remove pointless references to the file name itself and condense the
information so it wastes less space.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Link: https://lkml.kernel.org/r/20180314212030.412095827@linutronix.de

kernel/irq/timings.c

@@ -1,6 +1,4 @@
 /*
- * linux/kernel/irq/timings.c
- *
  * Copyright (C) 2016, Linaro Ltd - Daniel Lezcano <daniel.lezcano@linaro.org>
  *
  * This program is free software; you can redistribute it and/or modify