USB: usbtest: support test device with only one iso-in or iso-out endpoint

It is very common that one altsetting may include only one iso-in or iso-out
single endpoint, especially for high bandwidth endpoint, so support it.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/misc/usbtest.c

@@ -136,7 +136,7 @@ get_endpoints (struct usbtest_dev *dev, struct usb_interface *intf)
 					iso_out = e;
 			}
 		}
-		if ((in && out)  ||  (iso_in && iso_out))
+		if ((in && out)  ||  iso_in || iso_out)
 			goto found;
 	}
 	return -EINVAL;
@@ -162,6 +162,9 @@ get_endpoints (struct usbtest_dev *dev, struct usb_interface *intf)
 		dev->in_iso_pipe = usb_rcvisocpipe (udev,
 				iso_in->desc.bEndpointAddress
 					& USB_ENDPOINT_NUMBER_MASK);
+	}
+
+	if (iso_out) {
 		dev->iso_out = &iso_out->desc;
 		dev->out_iso_pipe = usb_sndisocpipe (udev,
 				iso_out->desc.bEndpointAddress