Revert "mmc: core: fix the clock scaling handling"

This reverts commit c77e1c54.
Now that we are getting the actual frequency value in devfreq target
function, we don't need to look for frequency being set to UINT_MAX.

Change-Id: I2194456d1b29a685fbade2159599303353fad00d
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>