drm/tegra: fix opencoded use of drm_panel_*

Use the drm_panel_get_modes function.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: linux-tegra@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20190804201637.1240-10-sam@ravnborg.org

drivers/gpu/drm/tegra/output.c

@@ -23,7 +23,7 @@ int tegra_output_connector_get_modes(struct drm_connector *connector)
 	 * ignore any other means of obtaining a mode.
 	 */
 	if (output->panel) {
-		err = output->panel->funcs->get_modes(output->panel);
+		err = drm_panel_get_modes(output->panel);
 		if (err > 0)
 			return err;
 	}