wifi: mt76: mt7603: disable A-MSDU tx support on MT7628

It was reported that this can cause the PSE hang issues, even with a low
number of fragments.

Link: openwrt/mt76#793 (comment)
Signed-off-by: Felix Fietkau <nbd@nbd.name>

Author: nbd168

drivers/net/wireless/mediatek/mt76/mac80211.c

@@ -452,7 +452,8 @@ mt76_phy_init(struct mt76_phy *phy, struct ieee80211_hw *hw)
 	ieee80211_hw_set(hw, SUPPORTS_AMSDU_IN_AMPDU);
 	ieee80211_hw_set(hw, SUPPORTS_REORDERING_BUFFER);
 
-	if (!(dev->drv->drv_flags & MT_DRV_AMSDU_OFFLOAD)) {
+	if (!(dev->drv->drv_flags & MT_DRV_AMSDU_OFFLOAD) &&
+	    hw->max_tx_fragments > 1) {
 		ieee80211_hw_set(hw, TX_AMSDU);
 		ieee80211_hw_set(hw, TX_FRAG_LIST);
 	}

drivers/net/wireless/mediatek/mt76/mt7603/init.c

@@ -524,6 +524,7 @@ int mt7603_register_device(struct mt7603_dev *dev)
 	hw->max_rates = 3;
 	hw->max_report_rates = 7;
 	hw->max_rate_tries = 11;
+	hw->max_tx_fragments = 1;
 
 	hw->radiotap_timestamp.units_pos =
 		IEEE80211_RADIOTAP_TIMESTAMP_UNIT_US;