x86: move disabled_cpus to common header

disabled_cpus is (up to now) a x86_64-only contruction.
But it's extern declaration can be moved to common header anyway

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/smp.h b/include/asm-x86/smp.h
index 9620165..be8a511 100644
--- a/include/asm-x86/smp.h
+++ b/include/asm-x86/smp.h
@@ -2,6 +2,7 @@
 #define _ASM_X86_SMP_H_
 #ifndef __ASSEMBLY__
 #include <linux/cpumask.h>
+#include <linux/init.h>
 
 extern cpumask_t cpu_callout_map;
 
@@ -60,6 +61,8 @@
 void native_smp_prepare_cpus(unsigned int max_cpus);
 void native_smp_cpus_done(unsigned int max_cpus);
 int native_cpu_up(unsigned int cpunum);
+
+extern unsigned disabled_cpus;
 #endif
 
 #ifdef CONFIG_X86_32