workqueue: remove useless WARN_ON_ONCE()

The @cpu is fetched via smp_processor_id() in this function,
so the check is useless.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

kernel/workqueue.c

@@ -4461,8 +4461,6 @@ static void wq_unbind_fn(struct work_struct *work)
 	struct worker *worker;
 
 	for_each_cpu_worker_pool(pool, cpu) {
-		WARN_ON_ONCE(cpu != smp_processor_id());
-
 		mutex_lock(&pool->attach_mutex);
 		spin_lock_irq(&pool->lock);