myri10ge: fix restoring of multicast list after reset

Don't count on whatever implementation artifact preserves the
multicast list across a reset cmd, and setup multicast filtering
as part of our reset routine.

The setting of allmulti when adopting firmware with the rx-filter
broadcast bug is also moved into the multicast setup routine where
it belongs.

Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>