drivers: mmc: msm: remove clock disable in probe

The probe function adds the MMC host which can start accepting request
immediately. There is an assumption here that no requests happen
immediatly, but it's not always the case. This assumption can causes
a BUG() when the clocks are disabled. The fix is to just remove the
clock disable in the probe function.

Signed-off-by: Daniel Walker <dwalker@codeaurora.org>