mmc: sdhci: Change O2 Host HS200 mode clock frequency to 200MHz

O2 SD Host HS200 mode clock frequency current is 208MHz, should be changed
to 200MHz to meet specification.

Signed-off-by: ernest.zhang <ernest.zhang@bayhubtech.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>