drm/vmwgfx/stdu: Use drm_mode_config_reset

When converting to atomic the state reset was done by directly calling
the functions, and before the modeset object was fully initialized.
This means the various ->dev pointers weren't set up.

After

commit 51f644b
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Fri Jun 12 18:00:49 2020 +0200

    drm/atomic-helper: reset vblank on crtc reset

this started to oops because now we're trying to derefence
drm_crtc->dev. Fix this up by entirely switching over to
drm_mode_config_reset, called once everything is set up.

Fixes: 51f644b ("drm/atomic-helper: reset vblank on crtc reset")
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Tested-by: Roland Scheidegger <sroland@vmware.com>
Signed-off-by: Roland Scheidegger <sroland@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c

@@ -1738,8 +1738,6 @@ static int vmw_stdu_init(struct vmw_private *dev_priv, unsigned unit)
 	stdu->base.is_implicit = false;
 
 	/* Initialize primary plane */
-	vmw_du_plane_reset(primary);
-
 	ret = drm_universal_plane_init(dev, primary,
 				       0, &vmw_stdu_plane_funcs,
 				       vmw_primary_plane_formats,
@@ -1754,8 +1752,6 @@ static int vmw_stdu_init(struct vmw_private *dev_priv, unsigned unit)
 	drm_plane_enable_fb_damage_clips(primary);
 
 	/* Initialize cursor plane */
-	vmw_du_plane_reset(cursor);
-
 	ret = drm_universal_plane_init(dev, cursor,
 			0, &vmw_stdu_cursor_funcs,
 			vmw_cursor_plane_formats,
@@ -1769,8 +1765,6 @@ static int vmw_stdu_init(struct vmw_private *dev_priv, unsigned unit)
 
 	drm_plane_helper_add(cursor, &vmw_stdu_cursor_plane_helper_funcs);
 
-	vmw_du_connector_reset(connector);
-
 	ret = drm_connector_init(dev, connector, &vmw_stdu_connector_funcs,
 				 DRM_MODE_CONNECTOR_VIRTUAL);
 	if (ret) {
@@ -1798,7 +1792,6 @@ static int vmw_stdu_init(struct vmw_private *dev_priv, unsigned unit)
 		goto err_free_encoder;
 	}
 
-	vmw_du_crtc_reset(crtc);
 	ret = drm_crtc_init_with_planes(dev, crtc, &stdu->base.primary,
 					&stdu->base.cursor,
 					&vmw_stdu_crtc_funcs, NULL);
@@ -1894,6 +1887,8 @@ int vmw_kms_stdu_init_display(struct vmw_private *dev_priv)
 		}
 	}
 
+	drm_mode_config_reset(dev);
+
 	DRM_INFO("Screen Target Display device initialized\n");
 
 	return 0;