mt76: mt76x02u: fix possible memory leak in __mt76x02u_mcu_send_msg

Free the skb if mt76u_bulk_msg fails in __mt76x02u_mcu_send_msg routine.

Fixes: 4c89ff2c ("mt76: split __mt76u_mcu_send_msg and mt76u_mcu_send_msg routines")
Co-developed-by: Gergo Koteles <soyer@irl.hu>
Signed-off-by: Gergo Koteles <soyer@irl.hu>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt76x02_usb_mcu.c

@@ -108,7 +108,7 @@ __mt76x02u_mcu_send_msg(struct mt76_dev *dev, struct sk_buff *skb,
 	ret = mt76u_bulk_msg(dev, skb->data, skb->len, NULL, 500,
 			     MT_EP_OUT_INBAND_CMD);
 	if (ret)
-		return ret;
+		goto out;
 
 	if (wait_resp)
 		ret = mt76x02u_mcu_wait_resp(dev, seq);