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>

arch/x86/kernel/tsc_32.c

@@ -256,9 +256,7 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
 						ref_freq, freq->new);
 			if (!(freq->flags & CPUFREQ_CONST_LOOPS)) {
 				tsc_khz = cpu_khz;
-				preempt_disable();
-				set_cyc2ns_scale(cpu_khz, smp_processor_id());
-				preempt_enable();
+				set_cyc2ns_scale(cpu_khz, freq->cpu);
 				/*
 				 * TSC based sched_clock turns
 				 * to junk w/ cpufreq

arch/x86/kernel/tsc_64.c

@@ -148,9 +148,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 			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;
 }