Only allocate per cpu data for possible CPUs, not compiled in CPUs.

Saves some memory except for hotplug situations.

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/arch/x86_64/kernel/setup64.c
===================================================================
--- linux.orig/arch/x86_64/kernel/setup64.c
+++ linux/arch/x86_64/kernel/setup64.c
@@ -94,7 +94,7 @@ void __init setup_per_cpu_areas(void)
 		size = PERCPU_ENOUGH_ROOM;
 #endif
 
-	for (i = 0; i < NR_CPUS; i++) { 
+	for_each_cpu_mask (i, cpu_possible_map) {
 		char *ptr;
 
 		if (!NODE_DATA(cpu_to_node(i))) {