new PHY @ e1000 - 2nd try

Add 82541ER device with latest integrated IGP2 PHY.
Introduced CONFIG_E1000_FALLBACK_MAC for NIC bring-up with empty eeprom.

Signed-off-by: Andre Schwarz <andre.schwarz@matrix-vision.de>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>