drm/drv: Make use of local variable driver in drm_dev_register()

There is a local variable that contains dev->driver. Make use of it
instead of "open coding" it.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221219183147.1639399-1-u.kleine-koenig@pengutronix.de

drivers/gpu/drm/drm_drv.c

@@ -889,8 +889,8 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
 
 	dev->registered = true;
 
-	if (dev->driver->load) {
-		ret = dev->driver->load(dev, flags);
+	if (driver->load) {
+		ret = driver->load(dev, flags);
 		if (ret)
 			goto err_minors;
 	}