scsi: ufs-msm: avoid powering off the device during system suspend

Powering off the device during system suspend cause regressions
and device may go bad. This is mainly because of specification
violation of not holding RST_n line LOW during power up. Since
RST_n line cannot be controlled from software, avoid powering off
the device in first place.

Change-Id: I5cdb3b3b1685222d69717f079dc9fc43c97b01bf
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>