net: 3com: typhoon: fix typhoon_get_link_ksettings

When moving from typhoon_get_settings to typhoon_getlink_ksettings
in the commit f7a5537c ("net: 3com: typhoon: use new api
ethtool_{get|set}_link_ksettings"), we use a local variable supported
but we forgot to update the struct ethtool_link_ksettings with
this value.

We also initialize advertising to zero, because otherwise it may
be uninitialized if no case of the switch (tp->xcvr_select) is used.

Signed-off-by: Philippe Reynes <tremyfr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>