of: unittest: Drop call to platform_set_drvdata(..., NULL)

The driver core already unsets driver data after .remove() completes.
So there is no reason to do this explicitly in the driver itself.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230319100620.295849-2-u.kleine-koenig@pengutronix.deSigned-off-by: Rob Herring <robh@kernel.org>

drivers/of/unittest.c

@@ -1639,7 +1639,6 @@ static int unittest_gpio_remove(struct platform_device *pdev)
 	if (devptr->chip.base != -1)
 		gpiochip_remove(&devptr->chip);
 
-	platform_set_drvdata(pdev, NULL);
 	kfree(devptr);
 
 	return 0;