arm64: dts: hisilicon: align 'freq-table-hz' with dtschema in UFS

The DT schema expects 'freq-table-hz' property to be an uint32-matrix,
which is also easier to read.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220306111125.116455-10-krzysztof.kozlowski@canonical.com