eepro100: Fix PXE boot

The phy handling was wrong for PXE, GPXE boot:
GPXE's eepro100 driver did not detect a valid link.

This is fixed here.

V2 - Use UPPER_CASE for enum values

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
