wifi: mt76: mt7921: don't disconnect when CSA to DFS chan

When station mode, don't disconnect when we get
channel switch from AP to DFS channel. Most APs
send CSA request after pass background CAC. In other
case we should disconnect after detect beacon miss.

Without patch when we get CSA to DFS channel get:
"kernel: wlo1: preparing for channel switch failed, disconnecting"

Fixes: 8aa2f59 ("wifi: mt76: mt7921: introduce CSA support")
Signed-off-by: Janusz Dziedzic <janusz.dziedzic@gmail.com>
Link: https://patch.msgid.link/20250716165443.28354-1-janusz.dziedzic@gmail.com
Signed-off-by: Felix Fietkau <nbd@nbd.name>

Author: januszdziedzic

drivers/net/wireless/mediatek/mt76/mt7921/main.c

@@ -1459,11 +1459,8 @@ static int mt7921_pre_channel_switch(struct ieee80211_hw *hw,
 	if (vif->type != NL80211_IFTYPE_STATION || !vif->cfg.assoc)
 		return -EOPNOTSUPP;
 
-	/* Avoid beacon loss due to the CAC(Channel Availability Check) time
-	 * of the AP.
-	 */
 	if (!cfg80211_chandef_usable(hw->wiphy, &chsw->chandef,
-				     IEEE80211_CHAN_RADAR))
+				     IEEE80211_CHAN_DISABLED))
 		return -EOPNOTSUPP;
 
 	return 0;