Revert "mmc: sdhci-msm: enable clock scaling capability"

This reverts commit 9cc95fde ("mmc: sdhci-msm: enable
clock scaling capability").
Clock scaling is breaking XO shutdown, keep the clock scaling
disabled till that issue is addressed.

Change-Id: Id4c530f8e2a8f565f9b957f46e5086078f808c96
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>