nl80211: Remove links when stopping AP MLD in hostapd

nl80211: Remove links when stopping AP MLD in hostapd

There is an issue when starting a non-MLD AP on the same interface that
previous operated as an AP MLD. When the previous AP MLD got stopped,
links were not removed when using hostapd. Next non-MLD AP will fail to
start because some nl80211 operations still require link id (e.g., set
freq).

Remove links when AP MLD is stop to avoid such issue. This was already
done in the deinit_ap() handler when using wpa_supplicant, but hostapd
needs to do same.

Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>