[POWERPC] Use __get_cpu_var in time.c

Use __get_cpu_var(x) instead of per_cpu(x, smp_processor_id()), as it
is optimized on ppc64 to access the current cpu's per-cpu offset directly;
it's local_paca.offset instead of TOC->paca[local_paca->processor_id].offset.

This is the trivial portion, two functions with one use each.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/time.c

@@ -327,7 +327,7 @@ void calculate_steal_time(void)
 
 	if (!cpu_has_feature(CPU_FTR_PURR))
 		return;
-	pme = &per_cpu(cpu_purr_data, smp_processor_id());
+	pme = &__get_cpu_var(cpu_purr_data);
 	if (!pme->initialized)
 		return;		/* this can happen in early boot */
 	tb = mftb();
@@ -352,7 +352,7 @@ static void snapshot_purr(void)
 	if (!cpu_has_feature(CPU_FTR_PURR))
 		return;
 	local_irq_save(flags);
-	pme = &per_cpu(cpu_purr_data, smp_processor_id());
+	pme = &__get_cpu_var(cpu_purr_data);
 	pme->tb = mftb();
 	pme->purr = mfspr(SPRN_PURR);
 	pme->initialized = 1;