percpu_counter: percpu_counter_hotcpu_callback() cleanup

In commit ebd8fef3 ("percpu_counter: make percpu_counters_lock
irq-safe") we disabled irqs in percpu_counter_hotcpu_callback()

We can grab every counter spinlock without having to disable
irqs again.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

lib/percpu_counter.c

@@ -176,13 +176,12 @@ static int percpu_counter_cpu_dead(unsigned int cpu)
 	spin_lock_irq(&percpu_counters_lock);
 	list_for_each_entry(fbc, &percpu_counters, list) {
 		s32 *pcount;
-		unsigned long flags;
 
-		raw_spin_lock_irqsave(&fbc->lock, flags);
+		raw_spin_lock(&fbc->lock);
 		pcount = per_cpu_ptr(fbc->counters, cpu);
 		fbc->count += *pcount;
 		*pcount = 0;
-		raw_spin_unlock_irqrestore(&fbc->lock, flags);
+		raw_spin_unlock(&fbc->lock);
 	}
 	spin_unlock_irq(&percpu_counters_lock);
 #endif