cfg80211: call disconnect_wk when AP stops

Since we now prevent regulatory restore during STA disconnect
if concurrent AP interfaces are active, we need to reschedule
this check when the AP state changes. This fixes never doing
a restore when an AP is the last interface to stop. Or to put
it another way: we need to re-check after anything we check
here changes.

Cc: stable@vger.kernel.org
Fixes: 113f3aaa

 ("cfg80211: Prevent regulatory restore during STA disconnect in concurrent interfaces")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>