dt-bindings: pwm: mxs: 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>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

Author: krzk

Documentation/devicetree/bindings/pwm/mxs-pwm.yaml

@@ -10,6 +10,9 @@ maintainers:
   - Shawn Guo <shawnguo@kernel.org>
   - Anson Huang <anson.huang@nxp.com>
 
+allOf:
+  - $ref: pwm.yaml#
+
 properties:
   compatible:
     enum:
@@ -28,7 +31,6 @@ properties:
 required:
   - compatible
   - reg
-  - "#pwm-cells"
   - fsl,pwm-number
 
 additionalProperties: false