x86: make additional_cpus static

This patch makes the needlessly global additional_cpus static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/smpboot.c

@@ -1306,7 +1306,7 @@ static void remove_siblinginfo(int cpu)
 	cpu_clear(cpu, cpu_sibling_setup_map);
 }
 
-int additional_cpus __initdata = -1;
+static int additional_cpus __initdata = -1;
 
 static __init int setup_additional_cpus(char *s)
 {