mt76: mt7615: clean up FWDL TXQ during/after firmware upload

Since we don't clean that tx queue from the tx tasklet, we need to do it
after the firmware upload is done. This patch also adds a cleanup step during
the upload, to help reclaim memory faster.

Fixes unprocessed queued frames eating up memory  long after the firmware
upload has already completed
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/mcu.c

@@ -248,6 +248,7 @@ static int mt7615_mcu_send_firmware(struct mt7615_dev *dev, const void *data,
 
 		data += cur_len;
 		len -= cur_len;
+		mt76_queue_tx_cleanup(dev, MT_TXQ_FWDL, false);
 	}
 
 	return ret;
@@ -525,6 +526,8 @@ static int mt7615_load_firmware(struct mt7615_dev *dev)
 		return -EIO;
 	}
 
+	mt76_queue_tx_cleanup(dev, MT_TXQ_FWDL, false);
+
 	dev_dbg(dev->mt76.dev, "Firmware init done\n");
 
 	return 0;