drm/hisilicon/kirin: Use simple encoder

The kirin 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/20200305155950.2705-7-tzimmermann@suse.de

drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c

@@ -24,6 +24,7 @@
 #include <drm/drm_of.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
 
 #include "dw_dsi_reg.h"
 
@@ -695,10 +696,6 @@ static const struct drm_encoder_helper_funcs dw_encoder_helper_funcs = {
 	.disable	= dsi_encoder_disable
 };
 
-static const struct drm_encoder_funcs dw_encoder_funcs = {
-	.destroy = drm_encoder_cleanup,
-};
-
 static int dw_drm_encoder_init(struct device *dev,
 			       struct drm_device *drm_dev,
 			       struct drm_encoder *encoder)
@@ -712,8 +709,7 @@ static int dw_drm_encoder_init(struct device *dev,
 	}
 
 	encoder->possible_crtcs = crtc_mask;
-	ret = drm_encoder_init(drm_dev, encoder, &dw_encoder_funcs,
-			       DRM_MODE_ENCODER_DSI, NULL);
+	ret = drm_simple_encoder_init(drm_dev, encoder, DRM_MODE_ENCODER_DSI);
 	if (ret) {
 		DRM_ERROR("failed to init dsi encoder\n");
 		return ret;