drm/rockchip: Drop explicit drm_mode_config_cleanup call

It's (almost, there's some iommu stuff without significance) right
above the drm_dev_put().

This is made possible by a preceeding patch which added a drmm_
cleanup action to drm_mode_config_init(), hence all we need to do to
ensure that drm_mode_config_cleanup() is run on final drm_device
cleanup is check the new error code for _init().

Aside: Another driver with a bit much devm_kzalloc, which should
probably use drmm_kzalloc instead ...

v2: Explain why this cleanup is possible (Laurent).

v3: Jump out at the right label (Francesco)

v4: Try again, kbuild caught that I didn't build test this properly
...

v5: Use drmm_mode_config_init() for more clarity (Sam, Thomas)

Acked-by: Sam Ravnborg <[e-mail]>
Cc: Sam Ravnborg <[e-mail]>
Cc: Thomas Zimmermann <[e-mail]>
Cc: Francesco Lavra <[e-mail]>
Cc: Laurent Pinchart <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Cc: Sandy Huang <[e-mail]>
Cc: "Heiko Stübner" <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/rockchip/rockchip_drm_drv.c

···
 	if (ret)
 		goto err_free;
 
-	drm_mode_config_init(drm_dev);
+	ret = drmm_mode_config_init(drm_dev);
+	if (ret)
+		goto err_iommu_cleanup;
 
 	rockchip_drm_mode_config_init(drm_dev);
 
 	/* Try to bind all sub drivers. */
 	ret = component_bind_all(dev, drm_dev);
 	if (ret)
-		goto err_mode_config_cleanup;
+		goto err_iommu_cleanup;
 
 	ret = drm_vblank_init(drm_dev, drm_dev->mode_config.num_crtc);
 	if (ret)
···
 	rockchip_drm_fbdev_fini(drm_dev);
 err_unbind_all:
 	component_unbind_all(dev, drm_dev);
-err_mode_config_cleanup:
-	drm_mode_config_cleanup(drm_dev);
+err_iommu_cleanup:
 	rockchip_iommu_cleanup(drm_dev);
 err_free:
-	drm_dev->dev_private = NULL;
-	dev_set_drvdata(dev, NULL);
 	drm_dev_put(drm_dev);
 	return ret;
 }
···
 
 	drm_atomic_helper_shutdown(drm_dev);
 	component_unbind_all(dev, drm_dev);
-	drm_mode_config_cleanup(drm_dev);
 	rockchip_iommu_cleanup(drm_dev);
 
-	drm_dev->dev_private = NULL;
-	dev_set_drvdata(dev, NULL);
 	drm_dev_put(drm_dev);
 }