[IA64] fix section mismatch in arch/ia64/kernel/topology.c

This patch silences:

	WARNING: vmlinux.o(.text+0x44672): Section mismatch in
	reference from the function arch_register_cpu() to the
	function .cpuinit.text:register_cpu()

Changes are based on codes in arch/x86/kernel/topology.c

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/asm-ia64/cpu.h b/include/asm-ia64/cpu.h
index e87fa32..fcca30b 100644
--- a/include/asm-ia64/cpu.h
+++ b/include/asm-ia64/cpu.h
@@ -14,8 +14,8 @@
 
 DECLARE_PER_CPU(int, cpu_state);
 
-extern int arch_register_cpu(int num);
 #ifdef CONFIG_HOTPLUG_CPU
+extern int arch_register_cpu(int num);
 extern void arch_unregister_cpu(int);
 #endif