x86/events: Remove last remnants of old filenames

Update to the new file paths, remove them from introductory comments.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170218113140.8051-1-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/events/intel/cstate.c

@@ -1,5 +1,5 @@
 /*
- * perf_event_intel_cstate.c: support cstate residency counters
+ * Support cstate residency counters
  *
  * Copyright (C) 2015, Intel Corp.
  * Author: Kan Liang (kan.liang@intel.com)