[PATCH] More ethtool support for sis900 and warning fix

  
  Add support to sis900 for the following ethtool ops:
        - get_link
        - get_settings
        - set_settings
        - nway_reset
  
Signed-off-by: Daniele Venzano <webvenza@libero.it>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>