kernel/sched.c: Suppress unused var warning

On UP:

  kernel/sched.c: In function 'wake_up_new_task':
  kernel/sched.c:2631: warning: unused variable 'cpu'

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -2650,7 +2650,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
 {
 	unsigned long flags;
 	struct rq *rq;
-	int cpu = get_cpu();
+	int cpu __maybe_unused = get_cpu();
 
 #ifdef CONFIG_SMP
 	/*