mmc: sdhci-s3c: Replace deprecated of_get_named_gpio()

mmc: sdhci-s3c: Replace deprecated of_get_named_gpio()

It seems the of_get_named_gpio() is solely used to check
if the GPIO is present in DT as the function can return 0
if and only if it's present and it becomes in the global
number space 0. But this quite likely shows that the code
wasn't ever been tested on the systems when no GPIO is provided.
In any case, the proper test is just to call of_property_present()
without any attempts in requesting GPIO (as we haven't saved the
number or descriptor anywhere in the code).

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20240307121912.3676850-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>