cpusets: Remove an unused variable

We don't use "cpu" any more after 2baab4e904 "sched: Fix
select_fallback_rq() vs cpu_active/cpu_online".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120328104608.GD29022@elgon.mountain
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/cpuset.c

@@ -2198,7 +2198,6 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
 void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
 {
 	const struct cpuset *cs;
-	int cpu;
 
 	rcu_read_lock();
 	cs = task_cs(tsk);