mmc: meson-mx-sdhc: Use devm_mmc_alloc_host() helper

mmc: meson-mx-sdhc: Use devm_mmc_alloc_host() helper

Use new function devm_mmc_alloc_host() to simplify the code.

Cc: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: linux-amlogic@lists.infradead.org
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/592c6674a83a80558e55b143c483e29dcbfef1fd.1748933789.git.zhoubinbin@loongson.cn
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>