myri10ge: report FIBER in ethtool for XFP based NIC

Make ethtool report FIBER for XFP based NIC's port type.
Don't bother to poke around and try to find out what is in
the XFP cage, since Linux does not have separate media types
for -SR -LR, etc.

Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off-by: Andrew Gallatin <gallatin@myri.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>