drm/fsl-dcu: Use simple encoder

The fsl-dcu driver uses an empty implementation for its encoder. 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/20200305155950.2705-5-tzimmermann@suse.de

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c

@@ -13,19 +13,11 @@
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
 
 #include "fsl_dcu_drm_drv.h"
 #include "fsl_tcon.h"
 
-static void fsl_dcu_drm_encoder_destroy(struct drm_encoder *encoder)
-{
-	drm_encoder_cleanup(encoder);
-}
-
-static const struct drm_encoder_funcs encoder_funcs = {
-	.destroy = fsl_dcu_drm_encoder_destroy,
-};
-
 int fsl_dcu_drm_encoder_create(struct fsl_dcu_drm_device *fsl_dev,
 			       struct drm_crtc *crtc)
 {
@@ -38,8 +30,8 @@ int fsl_dcu_drm_encoder_create(struct fsl_dcu_drm_device *fsl_dev,
 	if (fsl_dev->tcon)
 		fsl_tcon_bypass_enable(fsl_dev->tcon);
 
-	ret = drm_encoder_init(fsl_dev->drm, encoder, &encoder_funcs,
+	ret = drm_simple_encoder_init(fsl_dev->drm, encoder,
-			       DRM_MODE_ENCODER_LVDS, NULL);
+				      DRM_MODE_ENCODER_LVDS);
 	if (ret < 0)
 		return ret;