mt76: mt7615: fix possible memory leak in mt7615_mcu_wtbl_sta_add

Free the second mcu skb if __mt76_mcu_skb_send_msg() fails to transmit
the first one in mt7615_mcu_wtbl_sta_add().

Fixes: 99c457d902 ("mt76: mt7615: move mt7615_mcu_set_bmc to mt7615_mcu_ops")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

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

@@ -1293,8 +1293,12 @@ mt7615_mcu_wtbl_sta_add(struct mt7615_dev *dev, struct ieee80211_vif *vif,
 	skb = enable ? wskb : sskb;
 
 	err = __mt76_mcu_skb_send_msg(&dev->mt76, skb, cmd, true);
-	if (err < 0)
+	if (err < 0) {
+		skb = enable ? sskb : wskb;
+		dev_kfree_skb(skb);
+
 		return err;
+	}
 
 	cmd = enable ? MCU_EXT_CMD_STA_REC_UPDATE : MCU_EXT_CMD_WTBL_UPDATE;
 	skb = enable ? sskb : wskb;