mmc: mediatek: Use data tune for CMD line tune

If we don't select a set of better parameters for our emmc host,
It may easily occur CMD response CRC error. And also it may cause
cannot boot up issue.

Fot getting a set of better parameters, our emmc host supports
data tune mechanism.Therefore, our emmc driver also should change
to use data tune for CMD line.

Because our emmc host use the different clock source to sample the
CMD signal between HS200 and HS400 mode, the parameters are also
different between these two modes.
Separate cmd internal delay for HS200/HS400 mode.

This change can fix "System can not boot up" issue.
Signed-off-by: Yong Mao <yong.mao@mediatek.com>
Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>