dt-bindings: display: Add missing (unevaluated|additional)Properties on child nodes

In order to ensure only documented properties are present, node schemas
must have unevaluatedProperties or additionalProperties set to false
(typically).

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> # msm
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220823145649.3118479-11-robh@kernel.org