dt-bindings: arm: toshiba: add Toshiba Visconti ARM SoCs

Add device tree bindings for the Toshiba Visconti ARM SoCs.
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Reviewed-by: Punit Agrawal <punit1.agrawal@toshiba.co.jp>
Reviewed-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/toshiba.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/toshiba.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Toshiba Visconti Platform Device Tree Bindings
+
+maintainers:
+  - Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
+
+properties:
+  $nodename:
+    const: '/'
+  compatible:
+    oneOf:
+      - description: Visconti5 TMPV7708
+        items:
+          - const: toshiba,tmpv7708
+...