drm/mediatek/mtk_drm_crtc: Demote seriously out-of-date struct header

This needs someone with in-depth knowledge of the driver to complete.

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/mediatek/mtk_drm_crtc.c:62: warning: Function parameter or member 'pending_needs_vblank' not described in 'mtk_drm_crtc'
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c:62: warning: Function parameter or member 'event' not described in 'mtk_drm_crtc'
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c:62: warning: Function parameter or member 'layer_nr' not described in 'mtk_drm_crtc'
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c:62: warning: Function parameter or member 'pending_async_planes' not described in 'mtk_drm_crtc'
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c:62: warning: Function parameter or member 'cmdq_client' not described in 'mtk_drm_crtc'
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c:62: warning: Function parameter or member 'cmdq_event' not described in 'mtk_drm_crtc'
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c:62: warning: Function parameter or member 'hw_lock' not described in 'mtk_drm_crtc'

Cc: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mediatek@lists.infradead.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20201116174112.1833368-12-lee.jones@linaro.org

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -24,7 +24,7 @@
 #include "mtk_drm_gem.h"
 #include "mtk_drm_plane.h"
 
-/**
+/*
  * struct mtk_drm_crtc - MediaTek specific crtc structure.
  * @base: crtc object.
  * @enabled: records whether crtc_enable succeeded
@@ -34,6 +34,8 @@
  * @mutex: handle to one of the ten disp_mutex streams
  * @ddp_comp_nr: number of components in ddp_comp
  * @ddp_comp: array of pointers the mtk_ddp_comp structures used by this crtc
+ *
+ * TODO: Needs update: this header is missing a bunch of member descriptions.
  */
 struct mtk_drm_crtc {
 	struct drm_crtc			base;