drm/mediatek: dpi: Implement a CK/DE pol toggle in SoC config

drm/mediatek: dpi: Implement a CK/DE pol toggle in SoC config

Dp_intf does not support CK/DE polarity because the polarity information
is not used for eDP and DP while dp_intf is only for eDP and DP.
Therefore, we add a bit of flexibility to support SoCs without CK/DE pol
support.

Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20220701035845.16458-7-rex-bc.chen@mediatek.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>