dt-bindings: phy: g12a-usb2-phy: add optional power-domains

On newer SoCs, the USB2 PHY can require a power-domain to operate,
add it as optional.
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240605-topic-amlogic-upstream-bindings-fixes-power-domains-phy-v1-1-c819b0ecd8c8@linaro.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/amlogic,g12a-usb2-phy.yaml

@@ -41,6 +41,9 @@ properties:
       Phandle to a regulator that provides power to the PHY. This
       regulator will be managed during the PHY power on/off sequence.
 
+  power-domains:
+    maxItems: 1
+
 required:
   - compatible
   - reg