RDMA/mad: Delete inaccessible BUG_ON

There is no need to check existence of mad_queue, because we already did
pointer dereference before call to dequeue_mad().
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/mad.c

@@ -651,7 +651,6 @@ static void dequeue_mad(struct ib_mad_list_head *mad_list)
 	struct ib_mad_queue *mad_queue;
 	unsigned long flags;
 
-	BUG_ON(!mad_list->mad_queue);
 	mad_queue = mad_list->mad_queue;
 	spin_lock_irqsave(&mad_queue->lock, flags);
 	list_del(&mad_list->list);