mmc: mediatek: Add MMC_CAP_RUNTIME_RESUME support

Add MMC_CAP_RUNTIME_RESUME support to save resume time
Drop unnecessary SDC_ARG write

Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>