x86/time: Eliminate unused irq0_irqs counter

As of v2.6.38 this counter is being maintained without ever being
read.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/4F4787930200007800074A10@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/hardirq.h

@@ -7,7 +7,6 @@
 typedef struct {
 	unsigned int __softirq_pending;
 	unsigned int __nmi_count;	/* arch dependent */
-	unsigned int irq0_irqs;
 #ifdef CONFIG_X86_LOCAL_APIC
 	unsigned int apic_timer_irqs;	/* arch dependent */
 	unsigned int irq_spurious_count;

arch/x86/kernel/time.c

@@ -57,9 +57,6 @@ EXPORT_SYMBOL(profile_pc);
  */
 static irqreturn_t timer_interrupt(int irq, void *dev_id)
 {
-	/* Keep nmi watchdog up to date */
-	inc_irq_stat(irq0_irqs);
-
 	global_clock_event->event_handler(global_clock_event);
 
 	/* MCA bus quirk: Acknowledge irq0 by setting bit 7 in port 0x61 */