mmc: meson-mx-sdhc: Use devm_clk_hw_get_clk() for clock retrieval

Now that devm_clk_hw_get_clk() has been available for a while we can
resolve an older TODO where this API did not exist yet. No functional
changes intended.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20240217100200.1494980-2-martin.blumenstingl@googlemail.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>