mac80211: fix possible memory leak on AP CSA failure

If CSA for AP interface failed and the interface
was not stopped afterwards another CSA request
would leak sdata->u.ap.next_beacon.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Reviewed-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --cc net/mac80211/cfg.c
Simple merge