RDMA/mlx4: Remove NULL check before dev_{put, hold}

The call netdev_{put, hold} of dev_{put, hold} will check NULL,
so there is no need to check before using dev_{put, hold}.

Fix the following coccicheck warnings:
/drivers/infiniband/hw/mlx4/main.c:1311:2-10: WARNING:
WARNING  NULL check before dev_{put, hold} functions is not needed.

/drivers/infiniband/hw/mlx4/main.c:148:2-10: WARNING:
WARNING  NULL check before dev_{put, hold} functions is not needed.

/drivers/infiniband/hw/mlx4/main.c:1959:3-11: WARNING:
WARNING  NULL check before dev_{put, hold} functions is not needed.

/drivers/infiniband/hw/mlx4/main.c:1962:3-10: WARNING:
WARNING  NULL check before dev_{put, hold} functions is not needed.
Signed-off-by: zhang songyi <zhang.songyi@zte.com.cn>
Link: https://lore.kernel.org/r/202211291554079687539@zte.com.cnSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/mlx4/main.c

@@ -144,8 +144,7 @@ static struct net_device *mlx4_ib_get_netdev(struct ib_device *device,
 			}
 		}
 	}
-	if (dev)
-		dev_hold(dev);
+	dev_hold(dev);
 
 	rcu_read_unlock();
 	return dev;
@@ -1307,8 +1306,7 @@ int mlx4_ib_add_mc(struct mlx4_ib_dev *mdev, struct mlx4_ib_qp *mqp,
 
 	spin_lock_bh(&mdev->iboe.lock);
 	ndev = mdev->iboe.netdevs[mqp->port - 1];
-	if (ndev)
-		dev_hold(ndev);
+	dev_hold(ndev);
 	spin_unlock_bh(&mdev->iboe.lock);
 
 	if (ndev) {
@@ -1955,11 +1953,9 @@ static int mlx4_ib_mcg_detach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
 	if (ge) {
 		spin_lock_bh(&mdev->iboe.lock);
 		ndev = ge->added ? mdev->iboe.netdevs[ge->port - 1] : NULL;
-		if (ndev)
-			dev_hold(ndev);
+		dev_hold(ndev);
 		spin_unlock_bh(&mdev->iboe.lock);
-		if (ndev)
-			dev_put(ndev);
+		dev_put(ndev);
 		list_del(&ge->list);
 		kfree(ge);
 	} else