x86: unify x86_32 and x86_64 play_dead into one function

Add the new play_dead into smpboot.c, as it fits more cleanly in there
alongside other CONFIG_HOTPLUG functions.

Separate out the common code into its own function.

Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/smp.h b/include/asm-x86/smp.h
index 3bec6b4..17305e72 100644
--- a/include/asm-x86/smp.h
+++ b/include/asm-x86/smp.h
@@ -132,6 +132,7 @@
 int native_cpu_disable(void);
 void native_cpu_die(unsigned int cpu);
 void native_play_dead(void);
+void play_dead_common(void);
 
 void native_send_call_func_ipi(cpumask_t mask);
 void native_send_call_func_single_ipi(int cpu);