net/mlx4_core: Check device state before unregistering it

Verify that the device state is registered before un-registering it.
This check is required to prevent an OOPS on flows that do
re-registration of the device and its previous state was
unregistered.

Fixes: 225c7b1f ("IB/mlx4: Add a driver Mellanox ConnectX InfiniBand adapters")
Signed-off-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/intf.c

@@ -218,6 +218,9 @@ void mlx4_unregister_device(struct mlx4_dev *dev)
 	struct mlx4_priv *priv = mlx4_priv(dev);
 	struct mlx4_interface *intf;
 
+	if (!(dev->persist->interface_state & MLX4_INTERFACE_STATE_UP))
+		return;
+
 	mlx4_stop_catas_poll(dev);
 	mutex_lock(&intf_mutex);