mmc: sdhci-pltfm: Drop the use of sdhci_pltfm_free()

mmc: sdhci-pltfm: Drop the use of sdhci_pltfm_free()

Since the devm_mmc_alloc_host() helper is already in use,
sdhci_pltfm_free() is no longer needed.

To avoid causing drivers that still use sdhci_pltfm_free() to fail to
compile, it has been temporarily set to empty. And it will be removed
when there are no longer any callers.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/67e8881bc46f12aadbe82c655ce373b9c6907182.1749127796.git.zhoubinbin@loongson.cn
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>