[1/3] udc: net2280: Fix net2280_disable

Hi Alan,

My last proposal "udc: net2280: Fix overrun of OUT messages" is still
under investigation.

During the random stress tests I found a new rare problem:

When a request must be dequeued with net2280_dequeue() e.g. due
to a device clear action and the same request is finished by the
function scan_dma_completions():

https://elixir.bootlin.com/linux/v5.0-rc7/source/drivers/usb/gadget/udc/net2280.c#L1269

then the following search loop does not find the request and the function
returns the error -EINVAL without restoring the state ep->stopped = stopped!

https://elixir.bootlin.com/linux/v5.0-rc7/source/drivers/usb/gadget/udc/net2280.c#L1269

Thus the endpoint keeps blocked and does not receive any data.
When we insert ep->stopped = stopped here:

	if (&req->req != _req) {
		ep->stopped = stopped; // <<<<<----
		spin_unlock_irqrestore(&ep->dev->lock, flags);
		dev_err(&ep->dev->pdev->dev, "%s: Request mismatch\n",
								__func__);
		return -EINVAL;
	}

then the driver continues as expected, although the driver issues the
false error message "Request mismatch".

What do you think? It's labor-intensive to fix the error message here,
or shall we leave it as it is, and only insert the "ep->stopped = stopped;"

Regards,

Guido