[PATCH] sis190: basic sis191 support

The sis191 is the gigabit brother of the sis190. SiS's driver suggests
that the register set is backward compatible: this should hopefully
give a basic driver.

The device should allow the usual features from a modern ethernet
adapter (802.1q, SG, Jumbo frames, TSO, checksum offload). So far
the relevant register layout is not documented. SiS's driver does
not provide these features either (at least not for Linux).

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>