r8169: read MAC address from EEPROM on init (2nd attempt)

This is 2nd attempt to implement the initialization/reading of MAC address
from EEPROM. The first used PCI's VPD and there were some problems, some
devices are not able to read EEPROM content by VPD. The 2nd one uses direct
access to EEPROM through bit-banging interface and my testing results seem
to be much better.

I tested 5 systems each with different Realtek NICs and I didn't find any
problem. AFAIK Francois's NICs also works fine.

Original description:
This fixes the problem when MAC address is set by ifconfig or by
ip link commands and this address is stored in the device after
reboot. The power-off is needed to get right MAC address.
This is problem when Xen daemon is running because it renames the device
name from ethX to pethX and sets its MAC address to FE:FF:FF:FF:FF:FF.
After reboot the device is still using FE:FF:FF:FF:FF:FF.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>