NET: fix phy init for Asix AX88178 USB (GigE)

Asix provided this patch and I've confirmed "Plugable USB2-E1000" and
"Shenzhen Winstars NWU220G" USB dongles can get a link and TX/RX data.

Signed-off-by: "Freddy Xin" <freddy@asix.com.tw>
Signed-off-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>