dt-bindings: display: simple: allow panel-common properties

This device inherits properties from panel-common. Those should be allowed
to use, instead of specifying properties to true for each specific use.

Signed-off-by: Raphael Gallais-Pou <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Alexandre Torgue <[e-mail]>

Documentation/devicetree/bindings/display/panel/panel-simple.yaml

···
         # Yes Optoelectronics YTC700TLAG-05-201C 7" TFT LCD panel
       - yes-optoelectronics,ytc700tlag-05-201c
 
-  backlight: true
-  ddc-i2c-bus: true
-  enable-gpios: true
-  port: true
-  power-supply: true
-  no-hpd: true
-  hpd-gpios: true
-  data-mapping: true
-
 if:
   not:
     properties:
···
   properties:
     data-mapping: false
 
-additionalProperties: false
+unevaluatedProperties: false
 
 required:
   - compatible