x86: avoid section mismatch involving arch_register_cpu

Avoid section mismatch involving arch_register_cpu.

Marking arch_register_cpu as __init and removing the export
for non-hotplug-cpu configurations makes the following warning
go away:

Section mismatch in reference from the function
arch_register_cpu() to the function .devinit.text:register_cpu()
The function  arch_register_cpu() references
the function __devinit register_cpu().
This is often because arch_register_cpu lacks a __devinit
annotation or the annotation of register_cpu is wrong.

The only external user of arch_register_cpu in the tree is
in drivers/acpi/processor_core.c where it is guarded by
ACPI_HOTPLUG_CPU (which depends on HOTPLUG_CPU).

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
CC: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/topology.c

@@ -57,11 +57,10 @@ void arch_unregister_cpu(int num)
 }
 EXPORT_SYMBOL(arch_unregister_cpu);
 #else
-int arch_register_cpu(int num)
+static int __init arch_register_cpu(int num)
 {
 	return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
 }
-EXPORT_SYMBOL(arch_register_cpu);
 #endif /*CONFIG_HOTPLUG_CPU*/
 
 static int __init topology_init(void)

include/asm-x86/cpu.h

@@ -10,8 +10,9 @@
 struct x86_cpu {
 	struct cpu cpu;
 };
-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