dt-bindings: arm: mediatek: mmsys: Add VPPSYS compatible for MT8188

For MT8188, VPPSYS0 and VPPSYS1 are 2 display pipes with
hardware differences in power domains, clocks and subsystem counts,
which should be probed from mtk-mmsys driver to populate device by
platform_device_register_data then start its own clock driver.

Signed-off-by: yu-chang.lee <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Signed-off-by: AngeloGioacchino Del Regno <[e-mail]>

Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml

···
               - mediatek,mt8183-mmsys
               - mediatek,mt8186-mmsys
               - mediatek,mt8188-vdosys0
+              - mediatek,mt8188-vppsys0
+              - mediatek,mt8188-vppsys1
               - mediatek,mt8192-mmsys
               - mediatek,mt8195-vdosys1
               - mediatek,mt8195-vppsys0

Documentation/devicetree/bindings/clock/mediatek,mt8188-clock.yaml

···
       - mediatek,mt8188-vdecsys
       - mediatek,mt8188-vdecsys-soc
       - mediatek,mt8188-vencsys
-      - mediatek,mt8188-vppsys0
-      - mediatek,mt8188-vppsys1
       - mediatek,mt8188-wpesys
       - mediatek,mt8188-wpesys-vpp0