dt-bindings: Add missing 'unevaluatedProperties'

This doesn't yet do anything in the tools, but make it explicit so we can
check either 'unevaluatedProperties' or 'additionalProperties' is present
in schemas.

'unevaluatedProperties' is appropriate when including another schema (via
'$ref') and all possible properties and/or child nodes are not
explicitly listed in the schema with the '$ref'.

This is in preparation to add a meta-schema to check for missing
'unevaluatedProperties' or 'additionalProperties'. This has been a
constant source of review issues.

Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Wolfram Sang <wsa@kernel.org>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-By: Vinod Koul <vkoul@kernel.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://lore.kernel.org/r/20201005183830.486085-2-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>