drm/mediatek: Support MT8188 Padding in display driver

Padding is a new display module on MT8188, it provides ability
to add pixels to width and height of a layer with specified colors.

Due to hardware design, Mixer in VDOSYS1 requires width of a layer
to be 2-pixel-align, or 4-pixel-align when ETHDR is enabled,
we need Padding to deal with odd width.

Reviewed-by: CK Hu <ck.hu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20231214055847.4936-19-shawn.sung@mediatek.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>