[media] gspca: only set gspca->int_urb if submitting it succeeds

Currently alloc_and_submit_int_urb() is setting gspca->int_urb
as soon as the allocation has succeeded, but if the subsequent
submit fails, the urb gets destroyed. And then later will
get destroyed again in gspca_input_destroy_urb() because
gspca->int_urb is set, leading to a double free.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/gspca.c

@@ -224,12 +224,12 @@ static int alloc_and_submit_int_urb(struct gspca_dev *gspca_dev,
 		buffer, buffer_len,
 		int_irq, (void *)gspca_dev, interval);
 	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
-	gspca_dev->int_urb = urb;
 	ret = usb_submit_urb(urb, GFP_KERNEL);
 	if (ret < 0) {
 		PDEBUG(D_ERR, "submit int URB failed with error %i", ret);
 		goto error_submit;
 	}
+	gspca_dev->int_urb = urb;
 	return ret;
 
 error_submit: