dmfe/tulip: Let dmfe handle DM910x except for SPARC on-board chips

The Davicom DM9100 and DM9102 chips are used on the motherboards of
some SPARC systems (supported by the tulip driver) and also in PCI
expansion cards (supported by the dmfe driver).  There is no
difference in the PCI device ids for the two different configurations,
so these drivers both claim the device ids.  However, it is possible
to distinguish the two configurations by the presence of Open Firmware
properties for them, so we do that.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: David S. Miller <davem@davemloft.net>