matic media detection on Sun4m machines which support multiple media
(UTP and AUI). New function lenocarrier() switches media type when called
if no link? flags are set.
Redefine link flags for Lance ethernet (le):
<none>: switch between media as needed to find carrier (autodetect)
Preference to whatever the PROM is using (AUI if not booted
from the network)
link0: use UTP port only
link1: use AUI port only
This allows Sun4m machines with dual media Lance ethernet adapters to
boot from the network on the UTP port.