x86: remove export for smp_call_function_mask.

with this removal, exports for both i386 and x86_64,
regarding the "smp_call_function" series are now the same.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/smp_64.c

@@ -400,7 +400,6 @@ int native_smp_call_function_mask(cpumask_t mask,
 	spin_unlock(&call_lock);
 	return ret;
 }
-EXPORT_SYMBOL(smp_call_function_mask);
 
 /*
  * smp_call_function_single - Run a function on a specific CPU