Revert "cfg80211: make WEXT compatibility unselectable"

This reverts commit 24a0aa212ee2dbe44360288684478d76a8e20a0a.

It's causing severe userspace breakage. Namely, all the utilities from
wireless-utils which are relying on CONFIG_WEXT (which means tools like
'iwconfig', 'iwlist', etc) are not working anymore. There is a 'iw'
utility in newer wireless-tools, which is supposed to be a replacement
for all the "deprecated" binaries, but it's far away from being
massively adopted.

Please see [1] for example of the userspace breakage this is causing.

In addition to that, Larry Finger reports [2] that this patch is also
causing ipw2200 driver being impossible to build.

To me this clearly shows that CONFIG_WEXT is far, far away from being
"deprecated enough" to be removed.

[1] http://thread.gmane.org/gmane.linux.kernel/1857010
[2] http://thread.gmane.org/gmane.linux.network/343688

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>