mmc: sdhci-msm: Gate host controller clock during runtime suspend

Sdhci host controller suspend time is 100mSec while mmc host suspend
time is 3 seconds. So sdhci host controller will be inactive for ~3
seconds.
Gate clocks during runtime suspend.

Change-Id: I6ffd42623afb1e3dd198738b036a9b475745a19b
Signed-off-by: Ram Prakash Gupta <rampraka@codeaurora.org>