ASoC: dt-bindings: renesas,rz-ssi: Document the Renesas RZ/G3S SoC

The SSI IP variant present on the Renesas RZ/G3S SoC is similar to the
one found on the Renesas RZ/G2{UL, L, LC} SoCs. Add documentation for
it.

Acked-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Claudiu Beznea <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/sound/renesas,rz-ssi.yaml

···
           - renesas,r9a07g043-ssi  # RZ/G2UL and RZ/Five
           - renesas,r9a07g044-ssi  # RZ/G2{L,LC}
           - renesas,r9a07g054-ssi  # RZ/V2L
+          - renesas,r9a08g045-ssi  # RZ/G3S
       - const: renesas,rz-ssi
 
   reg: