arm: shmobile: Document Kingfisher board DT bindings

Add Kingfisher Device tree bindings Documentation, listing it as a
supported board.
Kingfisher is the H3ULCB/M3ULCB extension board.
Signed-off-by: NVladimir Barinov <vladimir.barinov@cogentembedded.com>
Acked-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

Documentation/devicetree/bindings/arm/shmobile.txt

@@ -78,6 +78,8 @@ Boards:
     compatible = "iwave,g20d", "iwave,g20m", "renesas,r8a7743"
   - iWave Systems RZ/G1M Qseven System On Module (iW-RainboW-G20M-Qseven)
     compatible = "iwave,g20m", "renesas,r8a7743"
+  - Kingfisher (SBEV-RCAR-KF-M03)
+    compatible = "shimafuji,kingfisher"
   - Koelsch (RTP0RC7791SEB00010S)
     compatible = "renesas,koelsch", "renesas,r8a7791"
   - Kyoto Microcomputer Co. KZM-A9-Dual