drm/mediatek: dpi: Add config to support direct connection to dpi panels

MediaTek dpi supports direct connection to dpi panels while dp_intf does
not support. Therefore, add a config "support_direct_pin" to control this.

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20220705102530.1344-3-rex-bc.chen@mediatek.com/


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