wireless: add back sysfs directory

wireless: add back sysfs directory

commit bfc8de46b40f43dfd541e6b7456c845d48e1a9c6 broke (at least)
Fedora's networking scripts, they check for the existence of the
wireless directory. As the files aren't used, add the directory
back and not the files. Also do it for both drivers based on the
old wireless extensions and cfg80211, regardless of whether the
compat code for wext is built into cfg80211 or not.

Cc: stable@vger.kernel.org [3.6]
Reported-by: Dave Airlie <airlied@gmail.com>
Reported-by: Bill Nottingham <notting@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>