drm/mediatek: ovl: Remove the color format comment for ovl_fmt_convert()

Since we changed MACROs to be consistent with DRM input color format
naming, the comment for ovl_fmt_conver() is no longer needed.

Fixes: 9f428b95 ("drm/mediatek: Add new color format MACROs in OVL")
Signed-off-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20241009034646.13143-4-jason-jh.lin@mediatek.com/


Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>