mmc: sdhci-sprd: Fix some resource leaks in the remove function

mmc: sdhci-sprd: Fix some resource leaks in the remove function

'sdhci_remove_host()' and 'sdhci_pltfm_free()' should be used in place of
'mmc_remove_host()' and 'mmc_free_host()'.

This avoids some resource leaks, is more in line with the error handling
path of the probe function, and is more consistent with other drivers.

Fixes: fb8bd90f83c4 ("mmc: sdhci-sprd: Add Spreadtrum's initial host controller")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Orson Zhai <orson.zhai@gmail.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20201217204236.163446-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>