mmc: sdhci_am654: 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.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/a456963bae14b0c6dade02f388f815f1ffcaa98a.1749127796.git.zhoubinbin@loongson.cn


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