mmc: sdhci-s3c: let device core setup the default pin configuration

With device core now able to setup the default pin configuration,
the call to devm_pinctrl_get_select_default can be removed. And
the pin configuration code based on the deprecated Samsung specific
gpio bindings is also removed.

Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>