Bluetooth: btusb: mediatek: Fix double free of skb in coredump

hci_devcd_append() would free the skb on error so the caller don't
have to free it again otherwise it would cause the double free of skb.

Fixes: 0b701513 ("Bluetooth: btusb: mediatek: add MediaTek devcoredump support")
Reported-by : Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

drivers/bluetooth/btmtk.c

@@ -380,8 +380,10 @@ int btmtk_process_coredump(struct hci_dev *hdev, struct sk_buff *skb)
 	switch (data->cd_info.state) {
 	case HCI_DEVCOREDUMP_IDLE:
 		err = hci_devcd_init(hdev, MTK_COREDUMP_SIZE);
-		if (err < 0)
+		if (err < 0) {
+			kfree_skb(skb);
 			break;
+		}
 		data->cd_info.cnt = 0;
 
 		/* It is supposed coredump can be done within 5 seconds */
@@ -407,9 +409,6 @@ int btmtk_process_coredump(struct hci_dev *hdev, struct sk_buff *skb)
 		break;
 	}
 
-	if (err < 0)
-		kfree_skb(skb);
-
 	return err;
 }
 EXPORT_SYMBOL_GPL(btmtk_process_coredump);