mmc: mediatek: refine msdc timeout api

Extract msdc timeout api common part to have
better code architecture and avoid redundant code.

Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/1595205759-5825-3-git-send-email-chun-hung.wu@mediatek.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>