arm64: dts: h3ulcb: add H3ULCB board DT bindings

Add H3ULCB Device tree bindings Documentation, listing it as a supported
board.
Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

Documentation/devicetree/bindings/arm/shmobile.txt

@@ -49,6 +49,8 @@ Boards:
     compatible = "renesas,genmai", "renesas,r7s72100"
   - Gose
     compatible = "renesas,gose", "renesas,r8a7793"
+  - H3ULCB (RTP0RC7795SKB00010S)
+    compatible = "renesas,h3ulcb", "renesas,r8a7795";
   - Henninger
     compatible = "renesas,henninger", "renesas,r8a7791"
   - Koelsch (RTP0RC7791SEB00010S)