mmc: Enable SD card clock scaling

The SD card clock scaling feature has a dependency on the
MMC_SDHCI_MSM which is not defined. Remove this dependency
so that the SD card clock scaling feature can be enabled.
In addition, fix the SD cards 2.0 initialization caused
by the incorrect clock settings.

Change-Id: I3eaec3546f89b86643b1937764288b3f39578c0e
Signed-off-by: Bao D. Nguyen <nguyenb@codeaurora.org>