wifi: mac80211: validate SCAN_FLAG_AP in scan request during MLO

When an AP interface is already beaconing, a subsequent scan is not allowed
unless the user space explicitly sets the flag NL80211_SCAN_FLAG_AP in the
scan request. If this flag is not set, the scan request will be returned
with the error code -EOPNOTSUPP. However, this restriction currently
applies only to non-ML interfaces. For ML interfaces, scans are allowed
without this flag being explicitly set by the user space which is wrong.
This is because the beaconing check currently uses only the deflink, which
does not get set during MLO.

Hence to fix this, during MLO, use the existing helper
ieee80211_num_beaconing_links() to know if any of the link is beaconing.

Signed-off-by: Aditya Kumar Singh <aditya.kumar.singh@oss.qualcomm.com>
Link: https://patch.msgid.link/20250516-bug_fix_mlo_scan-v2-1-12e59d9110ac@oss.qualcomm.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -2924,7 +2924,7 @@ static int ieee80211_scan(struct wiphy *wiphy,
 		 * the frames sent while scanning on other channel will be
 		 * lost)
 		 */
-		if (sdata->deflink.u.ap.beacon &&
+		if (ieee80211_num_beaconing_links(sdata) &&
 		    (!(wiphy->features & NL80211_FEATURE_AP_SCAN) ||
 		     !(req->flags & NL80211_SCAN_FLAG_AP)))
 			return -EOPNOTSUPP;