[PATCH] ieee80211softmac_io.c: fix warning "defined but not used"

Got this compiler warning and Johannes Berg <johannes@sipsolutions.net>
wrote:

Yeah, known 'bug', we have that code there but never use it. Feel free
to submit a patch (to John Linville, CC netdev and softmac-dev) to
remove it.

Signed-off-by: Toralf Foerster <toralf.foerster@gmx.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>