net/mlx4: prevent potential use after free in mlx4_en_do_uc_filter()

Print "entry->mac" before freeing "entry".  The "entry" pointer is
freed with kfree_rcu() so it's unlikely that we would trigger this
in real life, but it's safer to re-order it.

Fixes: cc5387f ("net/mlx4_en: Add unicast MAC filtering")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/aNvMHX4g8RksFFvV@stanley.mountain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Dan Carpenter

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

@@ -1180,9 +1180,9 @@ static void mlx4_en_do_uc_filter(struct mlx4_en_priv *priv,
 				mlx4_unregister_mac(mdev->dev, priv->port, mac);
 
 				hlist_del_rcu(&entry->hlist);
-				kfree_rcu(entry, rcu);
 				en_dbg(DRV, priv, "Removed MAC %pM on port:%d\n",
 				       entry->mac, priv->port);
+				kfree_rcu(entry, rcu);
 				++removed;
 			}
 		}