x86: io-apic - use ARRAY_SIZE macro

Make the code width a bit shorter with ARRAY_SIZE macro.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 93ceb19..9b01fda 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -166,7 +166,7 @@
 
 	memcpy(cfg, irq_cfg_legacy, sizeof(irq_cfg_legacy));
 
-	legacy_count = sizeof(irq_cfg_legacy)/sizeof(irq_cfg_legacy[0]);
+	legacy_count = ARRAY_SIZE(irq_cfg_legacy);
 	for (i = legacy_count; i < *da->nr; i++)
 		init_one_irq_cfg(&cfg[i]);