staging: comedi: ni_660x: ni_gpct_device_destroy() can handle a NULL pointer

Remove the unnecessary NULL pointer check.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_660x.c

@@ -1067,8 +1067,7 @@ static void ni_660x_detach(struct comedi_device *dev)
 	if (dev->irq)
 		free_irq(dev->irq, dev);
 	if (devpriv) {
-		if (devpriv->counter_dev)
-			ni_gpct_device_destroy(devpriv->counter_dev);
+		ni_gpct_device_destroy(devpriv->counter_dev);
 		ni_660x_free_mite_rings(dev);
 		mite_detach(devpriv->mite);
 	}