dt-bindings: arm-smmu: fix clocks/clock-names schema

Rework clocks/clock-names properties schema to properly describe
possible usage cases.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20221114170635.1406534-3-dmitry.baryshkov@linaro.org


Signed-off-by: Will Deacon <will@kernel.org>