dt-bindings: reset: renesas,rzv2h-usb2phy: Add '#mux-state-cells' property

Add the '#mux-state-cells' property to support describing the USB VBUS_SEL
multiplexer as a mux-controller in the Renesas RZ/V2H(P) USB2PHY binding.

The mux-controller cannot be integrated into the parent USB2PHY node
because the VBUS source selector is part of a separate hardware block,
not the USB2PHY block itself.

This is required to properly configure USB PHY power selection on
RZ/V2H(P) and RZ/G3E SoCs.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Documentation/devicetree/bindings/reset/renesas,rzv2h-usb2phy-reset.yaml

@@ -37,6 +37,9 @@ properties:
   '#reset-cells':
     const: 0
 
+  '#mux-state-cells':
+    const: 1
+
 required:
   - compatible
   - reg
@@ -44,6 +47,7 @@ required:
   - resets
   - power-domains
   - '#reset-cells'
+  - '#mux-state-cells'
 
 additionalProperties: false
 
@@ -58,4 +62,5 @@ examples:
         resets = <&cpg 0xaf>;
         power-domains = <&cpg>;
         #reset-cells = <0>;
+        #mux-state-cells = <1>;
     };