mmc: tmio: Fix timeout value for command request

Fix the problem which timeout occurs at the time of command request with
several cards.

The timeout value was insufficient as a verification of several cards,
so it was changed 5 seconds from 2 seconds.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>