dt-bindings: display: mediatek: modify VDOSYS0 display device tree Documentations for MT8188

modify VDOSYS0 display device tree Documentations for MT8188.

Signed-off-by: Nathan Lu <nathan.lu@mediatek.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20221206020046.11333-2-nathan.lu@mediatek.com/


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