drm/tegra: Use simple encoder

The tegra driver uses empty implementations for its encoders. Replace
the code with the generic simple encoder.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200305155950.2705-16-tzimmermann@suse.de

drivers/gpu/drm/tegra/drm.h

@@ -152,8 +152,6 @@ enum drm_connector_status
 tegra_output_connector_detect(struct drm_connector *connector, bool force);
 void tegra_output_connector_destroy(struct drm_connector *connector);
 
-void tegra_output_encoder_destroy(struct drm_encoder *encoder);
-
 /* from dpaux.c */
 struct drm_dp_aux *drm_dp_aux_find_by_of_node(struct device_node *np);
 enum drm_connector_status drm_dp_aux_detect(struct drm_dp_aux *aux);