i386: timer_irq_works() static again

timer_irq_works() needlessly became global.
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/i386/kernel/io_apic.c

@@ -1902,7 +1902,7 @@ __setup("no_timer_check", notimercheck);
  *	- if this function detects that timer IRQs are defunct, then we fall
  *	  back to ISA timer IRQs
  */
-int __init timer_irq_works(void)
+static int __init timer_irq_works(void)
 {
 	unsigned long t1 = jiffies;