wifi: mt76: mt7996: use the correct vif link for scanning/roc

restore fix which was dropped during MLO rework

Fixes: f0b0b23 ("wifi: mt76: mt7996: rework mt7996_mac_write_txwi() for MLO support")
Signed-off-by: Chad Monroe <chad@monroe.io>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/180fffd409aa57f535a3d2c1951e41ae398ce09e.1754659732.git.chad@monroe.io
Signed-off-by: Felix Fietkau <nbd@nbd.name>

Author: cmonroe

drivers/net/wireless/mediatek/mt76/mt7996/mac.c

@@ -903,8 +903,12 @@ void mt7996_mac_write_txwi(struct mt7996_dev *dev, __le32 *txwi,
 				       IEEE80211_TX_CTRL_MLO_LINK);
 
 	mvif = vif ? (struct mt7996_vif *)vif->drv_priv : NULL;
-	if (mvif)
-		mlink = rcu_dereference(mvif->mt76.link[link_id]);
+	if (mvif) {
+		if (wcid->offchannel)
+			mlink = rcu_dereference(mvif->mt76.offchannel_link);
+		if (!mlink)
+			mlink = rcu_dereference(mvif->mt76.link[link_id]);
+	}
 
 	if (mlink) {
 		omac_idx = mlink->omac_idx;