dt-bindings: arm: Document RZ/G2E SoC DT bindings

Add device tree bindings documentation for Renesas RZ/G2E (r8a774c0)
SoC.
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

Documentation/devicetree/bindings/arm/shmobile.txt

@@ -27,6 +27,8 @@ SoCs:
     compatible = "renesas,r8a77470"
   - RZ/G2M (R8A774A1)
     compatible = "renesas,r8a774a1"
+  - RZ/G2E (RA8774C0)
+    compatible = "renesas,r8a774c0"
   - R-Car M1A (R8A77781)
     compatible = "renesas,r8a7778"
   - R-Car H1 (R8A77790)