dt-bindings: gpu: samsung: constrain clocks in top-level properties

dt-bindings: gpu: samsung: constrain clocks in top-level properties

When number of clock varies between variants, the Devicetree bindings
coding convention expects to have widest constraints in top-level
definition of the properties and narrow them in allOf:if:then block.

This is more readable and sometimes allows to spot some errors in the
bindings.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231112184403.3449-3-krzysztof.kozlowski@linaro.org
Signed-off-by: Rob Herring <robh@kernel.org>