dt-bindings: soc: renesas: Document R-Car X5H Ironhide

Document the compatible values for the Renesas R-Car X5H (R8A78000) SoC,
as used on the Renesas Ironhide board.

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

Documentation/devicetree/bindings/soc/renesas/renesas.yaml

···
           - const: renesas,r8a779mb
           - const: renesas,r8a7795
 
+      - description: R-Car X5H (R8A78000)
+        items:
+          - enum:
+              - renesas,ironhide    # Ironhide (RTP8A78000ASKB0F10S)
+          - const: renesas,r8a78000
+
       - description: RZ/N1D (R9A06G032)
         items:
           - enum: