r8169: Modify the mothod for PHY settings of RTL8111G

Replace the current settings with rtl_writephy and rtl_readphy.
For the hardware, the settings are same with previous ones. This
make the setting method like the previous chips.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>