dt-bindings: arm: toshiba: Add the TMPV7708 VisROBO VRB board

Add an entry for the Toshiba Visconti TMPV7708 VisROBO VRB board
(tmpv7708-visrobo-vrb) to the board/SoC bindings.
Signed-off-by: Yuji Ishikawa <yuji2.ishikawa@toshiba.co.jp>
Link: https://lore.kernel.org/r/20211014092703.15251-3-yuji2.ishikawa@toshiba.co.jpSigned-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>

Documentation/devicetree/bindings/arm/toshiba.yaml

@@ -18,6 +18,7 @@ properties:
         items:
           - enum:
               - toshiba,tmpv7708-rm-mbrc  # TMPV7708 RM main board
+              - toshiba,tmpv7708-visrobo-vrb  # TMPV7708 VisROBO VRB board
           - const: toshiba,tmpv7708
 
 additionalProperties: true