perf, x86: P4_pmu_schedule_events -- use smp_processor_id instead of raw_

This snippet somehow escaped the commit:

 | commit 137351e0
 | Author: Cyrill Gorcunov <gorcunov@openvz.org>
 | Date:   Sat May 8 15:25:52 2010 +0400
 |
 |    x86, perf: P4 PMU -- protect sensible procedures from preemption

so bring it eventually back. It helps to catch
preemption issue (if there will be, rule of thumb --
don't use raw_ if you can).

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100518212439.167259349@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>