ASoC: dt-bindings: samsung-i2s: drop unneeded assigned-clock*

assigned-clock-parents and assigned-clocks are coming from dtschema, so
there is no need anymore to keep them in bindings. Their presence were
also causing false positives:

exynos5422-odroidxu3.dtb: i2s@3830000: Unevaluated properties are not allowed ('assigned-clock-rates' was unexpected)

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230120153020.320270-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>