drm/mediatek: dpi: Implement a swap_input toggle in SoC config

The hardware design of dp_intf does not support input swap, so we add
a bit of flexibility to support SoCs without swap_input support.
We also add a warning message if the hardware is not supported and it
needs to swap input.

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/20220701035845.16458-8-rex-bc.chen@mediatek.com/


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