pasemi_mac: ethtool set settings support

Add ethtool set settings to pasemi_mac_ethtool.

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>