nl80211: Don't try to scan on AP interface with active links

nl80211: Don't try to scan on AP interface with active links

When the kernel driver doesn't support scanning on an AP interface,
nl80211 drivers attempts to switch to station interface to perform a
scan. However, when the AP is affiliated with an AP MLD and there are
already active links this is not valid. In such a case, fail the scan.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>