x86: perf_counter.c intel_perfmon_event_map and max_intel_perfmon_events should be static

Impact: cleanup, avoid sparse warnings, reduce kernel size a bit

Fixes these sparse warnings:
 arch/x86/kernel/cpu/perf_counter.c:44:11: warning: symbol 'intel_perfmon_event_map' was not declared. Should it be static?
 arch/x86/kernel/cpu/perf_counter.c:54:11: warning: symbol 'max_intel_perfmon_events' was not declared. Should it be static?

Signed-off-by: Jaswinder Singh <jaswinder@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>