dt-bindings: reset: renesas,rzg2l-usbphy-ctrl: Document RZ/G2UL USBPHY Control bindings

Add device tree binding document for RZ/G2UL USBPHY Control Device.
RZ/G2UL USBPHY Control Device is identical to one found on the RZ/G2L SoC.
No driver changes are required as generic compatible string
"renesas,rzg2l-usbphy-ctrl" will be used as a fallback.

Signed-off-by: Biju Das <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Philipp Zabel <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/reset/renesas,rzg2l-usbphy-ctrl.yaml

···
   compatible:
     items:
       - enum:
+          - renesas,r9a07g043-usbphy-ctrl # RZ/G2UL
           - renesas,r9a07g044-usbphy-ctrl # RZ/G2{L,LC}
           - renesas,r9a07g054-usbphy-ctrl # RZ/V2L
       - const: renesas,rzg2l-usbphy-ctrl