x86, perf: Change two init functions to static

init_hw_perf_events() is called via early_initcall now.
x86_pmu_event_init is x86_pmu member function.

So we can change them to static.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
LKML-Reference: <4D3A16F9.109@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>