x86: fix call to set_cyc2ns_scale() from time_cpufreq_notifier()

In time_cpufreq_notifier() the cpu id to act upon is held in freq->cpu. Use it
instead of smp_processor_id() in the call to set_cyc2ns_scale().
This makes the preempt_*able() unnecessary and lets set_cyc2ns_scale() update
the intended cpu's cyc2ns.

Related mail/thread: http://lkml.org/lkml/2007/12/7/130

Signed-off-by: Karsten Wiese <fzu@wemgehoertderstaat.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c
index 947554d..d3bebaa 100644
--- a/arch/x86/kernel/tsc_64.c
+++ b/arch/x86/kernel/tsc_64.c
@@ -148,9 +148,7 @@
 			mark_tsc_unstable("cpufreq changes");
 	}
 
-	preempt_disable();
-	set_cyc2ns_scale(tsc_khz_ref, smp_processor_id());
-	preempt_enable();
+	set_cyc2ns_scale(tsc_khz_ref, freq->cpu);
 
 	return 0;
 }