Move away from using net_device as the main structure in orinoco
function calls. Use orinoco_private instead.

This makes more sense when we move to cfg80211, and we get wiphys as
well.
Signed-off-by: NDavid Kilroy <kilroyd@googlemail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>