dt-bindings: pwm: toshiba,visconti: Include generic PWM schema

Include generic pwm.yaml schema, which enforces PWM node naming and
brings pwm-cells requirement.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

Documentation/devicetree/bindings/pwm/toshiba,pwm-visconti.yaml

@@ -9,6 +9,9 @@ title: Toshiba Visconti PWM Controller
 maintainers:
   - Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
 
+allOf:
+  - $ref: pwm.yaml#
+
 properties:
   compatible:
     items:
@@ -23,7 +26,6 @@ properties:
 required:
   - compatible
   - reg
-  - '#pwm-cells'
 
 additionalProperties: false