drm/mediatek: Add mt8186 dpi compatibles and platform data

Add the compatible because use edge_cfg_in_mmsys in mt8186.

Signed-off-by: Xinlei Lee <xinlei.lee@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/1666577099-3859-4-git-send-email-xinlei.lee@mediatek.com/


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