mt76: do not overwrite max_tx_fragments if it has been set

Prevent the overwriting of max_tx_fragments if it has already been set
in chip-specific init routine.

Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

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

@@ -287,7 +287,9 @@ mt76_phy_init(struct mt76_dev *dev, struct ieee80211_hw *hw)
 	wiphy->available_antennas_rx = dev->phy.antenna_mask;
 
 	hw->txq_data_size = sizeof(struct mt76_txq);
-	hw->max_tx_fragments = 16;
+
+	if (!hw->max_tx_fragments)
+		hw->max_tx_fragments = 16;
 
 	ieee80211_hw_set(hw, SIGNAL_DBM);
 	ieee80211_hw_set(hw, PS_NULLFUNC_STACK);