cfg80211: remove unused wext handler exports

A lot of code is dedicated to giving drivers the
ability to use cfg80211's wext handlers without
completely converting. However, only orinoco is
currently using this, and it is only partially
using it.

We reduce the size of both the source and binary
by removing those that nobody needs. If a driver
shows up that needs it during conversion, we can
add back those that are needed.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>