mmc: sdhci-s3c: constify uses of driver/match data

mmc: sdhci-s3c: constify uses of driver/match data

The driver data (struct sdhci_s3c_drv_data) stored in of_device_id
table is allocated as const and used only in const-way.  Skip
unnecessary const-away casts and convert all users to work with pointer
to const.  This is both more logical and safer.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Sylwester Nawrocki <snawrocki@kernel.org>
Link: https://lore.kernel.org/r/20210415084412.51125-3-krzysztof.kozlowski@canonical.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>