igb: read address from RAH/RAL instead of from EEPROM

Instead of pulling the mac address from EEPROM it is easier to pull it from
the RAL/RAH registers and then just copy it into the address structures.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>