net/mlx5e: Do not use netdev_err() before the netdev is registered

Since it is un-named at this time.

Signed-off-by: Achiad Shochat <achiad@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>