drm/tegra: Use __drm_atomic_helper_reset_connector for subclassing connector state, v2.

Changes since v1:
- Do not reset if state allocation fails.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Thierry Reding <treding@nvidia.com> #irc
Link: http://patchwork.freedesktop.org/patch/msgid/1451908400-25147-3-git-send-email-maarten.lankhorst@linux.intel.comSigned-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/tegra/dsi.c

@@ -745,14 +745,13 @@ static void tegra_dsi_soft_reset(struct tegra_dsi *dsi)
 
 static void tegra_dsi_connector_reset(struct drm_connector *connector)
 {
-	struct tegra_dsi_state *state;
-
-	kfree(connector->state);
-	connector->state = NULL;
+	struct tegra_dsi_state *state =
+		kzalloc(sizeof(*state), GFP_KERNEL);
 
-	state = kzalloc(sizeof(*state), GFP_KERNEL);
-	if (state)
-		connector->state = &state->base;
+	if (state) {
+		kfree(connector->state);
+		__drm_atomic_helper_connector_reset(connector, &state->base);
+	}
 }
 
 static struct drm_connector_state *