[IA64-SGI] sn_hwperf use of num_online_cpus()

Eliminate an unnecessary -- and flawed -- use of the expensive
num_online_cpus().

Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/sn/kernel/sn2/sn_hwperf.c

@@ -605,7 +605,7 @@ static int sn_hwperf_op_cpu(struct sn_hwperf_op_info *op_info)
 	op_info->a->arg &= SN_HWPERF_ARG_OBJID_MASK;
 
 	if (cpu != SN_HWPERF_ARG_ANY_CPU) {
-		if (cpu >= num_online_cpus() || !cpu_online(cpu)) {
+		if (cpu >= NR_CPUS || !cpu_online(cpu)) {
 			r = -EINVAL;
 			goto out;
 		}