- phy capability settings allows lower or equal capability as suggested
  in Realtek's changes;
- I/O voodoo;
- no need to s/mdio_write/RTL8169_WRITE_GMII_REG/;
- s/rtl8169_hw_PHY_config/rtl8169_hw_phy_config/;
- rtl8169_hw_phy_config(): ad-hoc struct "phy_magic" to limit duplication
  of code (yep, the u16 -> int conversions should work as expected);
- variable renames and whitepace changes ignored.