amd8111_nic fix

[Liu Tao]

Hello,

On my board I have amd8111 nic + realtek 8201 PHY,
but 8111nic use active high reset signal to reset PHY
while RTL8201 accepts active low reset signal. However
amd8111 nic provides PHY_RESET_POLARITY bit in CMD3 register,
so I add the "phy_lowreset" register to handle this.
attached is the patch.

Regards,
Liu Tao