scsi: ufs: Allowing power mode change

Due to M-PHY issues, moving from HS to any other mode or gear or
even Hibern8 causes some un-predicted behavior of the device.
This patch fixes this issues.

Change-Id: I4540e30703aa1212099b2316e158b09e311c7420
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>