staging: comedi: ni_mio_common: 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_mio_common.c

@@ -5675,8 +5675,6 @@ static void mio_common_detach(struct comedi_device *dev)
 {
 	struct ni_private *devpriv = dev->private;
 
-	if (devpriv) {
-		if (devpriv->counter_dev)
-			ni_gpct_device_destroy(devpriv->counter_dev);
-	}
+	if (devpriv)
+		ni_gpct_device_destroy(devpriv->counter_dev);
 }