mmc: mtk-sd: convert to devm_platform_ioremap_resource

Use devm_platform_ioremap_resource() to simplify code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Link: https://lore.kernel.org/r/20191215175120.3290-12-tiny.windzz@gmail.com


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