mmc: sdhci: Use devm_mmc_alloc_host() helper

mmc: sdhci: Use devm_mmc_alloc_host() helper

Use new function devm_mmc_alloc_host() to simplify the code.

Although sdhci_free_host() is no longer needed, to avoid drivers that still
use this function from failing to compile, sdhci_free_host() is temporarily
set to empty. Finally, it will be removed when there are no more callers.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/dcfce3ddf980563c590f82c1b4e8840c29497887.1749127796.git.zhoubinbin@loongson.cn
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>