x86: remove idle_timestamp from 32bit irq_cpustat_t

Impact: bogus irq_cpustat field removed

idle_timestamp is left over from the removed irqbalance code.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

arch/x86/include/asm/hardirq_32.h

@@ -6,7 +6,6 @@
 
 typedef struct {
 	unsigned int __softirq_pending;
-	unsigned long idle_timestamp;
 	unsigned int __nmi_count;	/* arch dependent */
 	unsigned int apic_timer_irqs;	/* arch dependent */
 	unsigned int irq0_irqs;

arch/x86/kernel/process_32.c

@@ -108,7 +108,6 @@ void cpu_idle(void)
 				play_dead();
 
 			local_irq_disable();
-			__get_cpu_var(irq_stat).idle_timestamp = jiffies;
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
 			pm_idle();