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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Nobuhiro Iwamatsu <[e-mail]>

Documentation/devicetree/bindings/arm/toshiba.yaml

···
         items:
           - enum:
               - toshiba,tmpv7708-rm-mbrc  # TMPV7708 RM main board
+              - toshiba,tmpv7708-visrobo-vrb  # TMPV7708 VisROBO VRB board
           - const: toshiba,tmpv7708
 
 additionalProperties: true