usb: gadget: uvc: Fix the wrong v4l2_device_unregister call

If an error occurred before calling the 'v4l2_device_register' func,
and then goto error, but no need to call 'v4l2_device_unregister'
func.

Signed-off-by: Zqiang <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/function/f_uvc.c

···
 	/* Initialise video. */
 	ret = uvcg_video_init(&uvc->video, uvc);
 	if (ret < 0)
-		goto error;
+		goto v4l2_error;
 
 	/* Register a V4L2 device. */
 	ret = uvc_register_video(uvc);
 	if (ret < 0) {
 		uvcg_err(f, "failed to register video device\n");
-		goto error;
+		goto v4l2_error;
 	}
 
 	return 0;
 
-error:
+v4l2_error:
 	v4l2_device_unregister(&uvc->v4l2_dev);
-
+error:
 	if (uvc->control_req)
 		usb_ep_free_request(cdev->gadget->ep0, uvc->control_req);
 	kfree(uvc->control_buf);