dt-bindings: iommu: ipmmu-vmsa: Add r8a774b1 support

Document RZ/G2N (R8A774B1) SoC bindings.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Documentation/devicetree/bindings/iommu/renesas,ipmmu-vmsa.txt

@@ -15,6 +15,7 @@ Required Properties:
     - "renesas,ipmmu-r8a7744" for the R8A7744 (RZ/G1N) IPMMU.
     - "renesas,ipmmu-r8a7745" for the R8A7745 (RZ/G1E) IPMMU.
     - "renesas,ipmmu-r8a774a1" for the R8A774A1 (RZ/G2M) IPMMU.
+    - "renesas,ipmmu-r8a774b1" for the R8A774B1 (RZ/G2N) IPMMU.
     - "renesas,ipmmu-r8a774c0" for the R8A774C0 (RZ/G2E) IPMMU.
     - "renesas,ipmmu-r8a7790" for the R8A7790 (R-Car H2) IPMMU.
     - "renesas,ipmmu-r8a7791" for the R8A7791 (R-Car M2-W) IPMMU.