RDMA/ipoib: Return void from ipoib_mcast_stop_thread()

The return value from ipoib_mcast_stop_thread() is always 0 - change it to
be void.

Link: https://lore.kernel.org/r/20200622092256.6931-1-kamalheib1@gmail.comSigned-off-by: Kamal Heib <kamalheib1@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/ulp/ipoib/ipoib.h

@@ -527,7 +527,7 @@ void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb);
 
 void ipoib_mcast_restart_task(struct work_struct *work);
 void ipoib_mcast_start_thread(struct net_device *dev);
-int ipoib_mcast_stop_thread(struct net_device *dev);
+void ipoib_mcast_stop_thread(struct net_device *dev);
 
 void ipoib_mcast_dev_down(struct net_device *dev);
 void ipoib_mcast_dev_flush(struct net_device *dev);

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

@@ -680,15 +680,13 @@ void ipoib_mcast_start_thread(struct net_device *dev)
 	spin_unlock_irqrestore(&priv->lock, flags);
 }
 
-int ipoib_mcast_stop_thread(struct net_device *dev)
+void ipoib_mcast_stop_thread(struct net_device *dev)
 {
 	struct ipoib_dev_priv *priv = ipoib_priv(dev);
 
 	ipoib_dbg_mcast(priv, "stopping multicast thread\n");
 
 	cancel_delayed_work_sync(&priv->mcast_task);
-
-	return 0;
 }
 
 static int ipoib_mcast_leave(struct net_device *dev, struct ipoib_mcast *mcast)