Bluetooth: btusb: Fix memleak in btusb_mtk_submit_wmt_recv_urb

When kmalloc() on buf fails, urb should be freed just like
when kmalloc() on dr fails.
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btusb.c

@@ -2896,6 +2896,7 @@ static int btusb_mtk_submit_wmt_recv_urb(struct hci_dev *hdev)
 	buf = kmalloc(size, GFP_KERNEL);
 	if (!buf) {
 		kfree(dr);
+		usb_free_urb(urb);
 		return -ENOMEM;
 	}