dt-bindings: soc: mediatek: Add support for MT8188 VPPSYS

Add compatible for MT8188 VPP mutex, having different bits to activate
mute for various hardware IPs.
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240322092845.381313-2-angelogioacchino.delregno@collabora.comSigned-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Documentation/devicetree/bindings/soc/mediatek/mediatek,mutex.yaml

@@ -33,6 +33,7 @@ properties:
       - mediatek,mt8186-disp-mutex
       - mediatek,mt8186-mdp3-mutex
       - mediatek,mt8188-disp-mutex
+      - mediatek,mt8188-vpp-mutex
       - mediatek,mt8192-disp-mutex
       - mediatek,mt8195-disp-mutex
       - mediatek,mt8195-vpp-mutex