perf/x86/intel: Fix regression by default disabling perfmon v4 interrupt handling

perf/x86/intel: Fix regression by default disabling perfmon v4 interrupt handling

Kyle Huey reported that 'rr', a replay debugger, broke due to the following commit:

  aa3c7c177b6d ("perf/x86/intel: Add a separate Arch Perfmon v4 PMI handler")

Rework the 'disable_counter_freezing' __setup() parameter such that we
can explicitly enable/disable it and switch to default disabled.

To this purpose, rename the parameter to "perf_v4_pmi=" which is a much
better description and allows requiring a bool argument.

[ mingo: Improved the changelog some more. ]

Reported-by: Kyle Huey <me@kylehuey.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert O'Callahan <robert@ocallahan.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Link: http://lkml.kernel.org/r/20181120170842.GZ2131@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>