media: dvb-usb-v2: Fix incorrect use of transfer_flags URB_FREE_BUFFER

commit 1a0c10ed ("media: dvb-usb-v2: stop using coherent memory for
URBs") incorrectly adds URB_FREE_BUFFER after every urb transfer.

It cannot use this flag because it reconfigures the URBs accordingly
to suit connected devices. In doing a call to usb_free_urb is made and
invertedly frees the buffers.

The stream buffer should remain constant while driver is up.
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
CC: stable@vger.kernel.org # v4.18+
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/dvb-usb-v2/usb_urb.c

@@ -155,7 +155,6 @@ static int usb_urb_alloc_bulk_urbs(struct usb_data_stream *stream)
 				stream->props.u.bulk.buffersize,
 				usb_urb_complete, stream);
 
-		stream->urb_list[i]->transfer_flags = URB_FREE_BUFFER;
 		stream->urbs_initialized++;
 	}
 	return 0;
@@ -186,7 +185,7 @@ static int usb_urb_alloc_isoc_urbs(struct usb_data_stream *stream)
 		urb->complete = usb_urb_complete;
 		urb->pipe = usb_rcvisocpipe(stream->udev,
 				stream->props.endpoint);
-		urb->transfer_flags = URB_ISO_ASAP | URB_FREE_BUFFER;
+		urb->transfer_flags = URB_ISO_ASAP;
 		urb->interval = stream->props.u.isoc.interval;
 		urb->number_of_packets = stream->props.u.isoc.framesperurb;
 		urb->transfer_buffer_length = stream->props.u.isoc.framesize *
@@ -210,7 +209,7 @@ static int usb_free_stream_buffers(struct usb_data_stream *stream)
 	if (stream->state & USB_STATE_URB_BUF) {
 		while (stream->buf_num) {
 			stream->buf_num--;
-			stream->buf_list[stream->buf_num] = NULL;
+			kfree(stream->buf_list[stream->buf_num]);
 		}
 	}