[IA64] another place to use for_each_cpu_mask() in arch/ia64

In arch/ia64 change the explicit use of a for-loop using NR_CPUS into the
general for_each_online_cpu() construct.  This widens the scope of potential
future optimizations of the general constructs, as well as takes advantage
of the existing optimizations of first_cpu() and next_cpu(), which is
advantageous when the true CPU count is much smaller than NR_CPUS.
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/mca.c

@@ -508,9 +508,7 @@ ia64_mca_wakeup_all(void)
 	int cpu;
 
 	/* Clear the Rendez checkin flag for all cpus */
-	for(cpu = 0; cpu < NR_CPUS; cpu++) {
-		if (!cpu_online(cpu))
-			continue;
+	for_each_online_cpu(cpu) {
 		if (ia64_mc_info.imi_rendez_checkin[cpu] == IA64_MCA_RENDEZ_CHECKIN_DONE)
 			ia64_mca_wakeup(cpu);
 	}