pasemi_mac: ethtool get settings fix

Not all pasemi mac interfaces can have a phy attached.
For example, XAUI has no phy and phydev is NULL for it.
In this case ethtool get settings causes kernel crash.
Fix it by returning -EOPNOTSUPP if there's no PHY attached.

Signed-off-by: Valentine Barshak <vbarshak@ru.mvista.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: David S. Miller <davem@davemloft.net>