xhci: Don't always run the default stop endpoint command completion handler

The default stop endpoint completion handler will give back cancelled
URBs, and clean, or move past those canceller TRBs on the ring.

This is not always the preferred action.

If the stop endpoint command issuer is waiting for a completion
skip the default handler and just call the completion.
Signed-off-by: NMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -1436,7 +1436,8 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 	case TRB_STOP_RING:
 		WARN_ON(slot_id != TRB_TO_SLOT_ID(
 				le32_to_cpu(cmd_trb->generic.field[3])));
-		xhci_handle_cmd_stop_ep(xhci, slot_id, cmd_trb, event);
+		if (!cmd->completion)
+			xhci_handle_cmd_stop_ep(xhci, slot_id, cmd_trb, event);
 		break;
 	case TRB_SET_DEQ:
 		WARN_ON(slot_id != TRB_TO_SLOT_ID(