[IA64] kexec: Fix CONFIG_SMP=n compilation

Kexec support for 2.6.20 on ia64 does not build properly using a config
made up by CONFIG_SMP=n and CONFIG_HOTPLUG_CPU=n:

Signed-off-by: Magnus Damm <magnus@valinux.co.jp>
Acked-by: Simon Horman <horms@verge.net.au>
Acked-by: Jay Lan <jlan@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/machine_kexec.c b/arch/ia64/kernel/machine_kexec.c
index e2ccc9f..7141795 100644
--- a/arch/ia64/kernel/machine_kexec.c
+++ b/arch/ia64/kernel/machine_kexec.c
@@ -70,12 +70,14 @@
 
 void machine_shutdown(void)
 {
+#ifdef CONFIG_HOTPLUG_CPU
 	int cpu;
 
 	for_each_online_cpu(cpu) {
 		if (cpu != smp_processor_id())
 			cpu_down(cpu);
 	}
+#endif
 	kexec_disable_iosapic();
 }