scsi: ufs: fix a compilation warning

Assign a value to 'ret' in order to prevent a compilation warning of:
'ret' may be used uninitialized in this function.

Change-Id: Id10d0e5e8204d233cf4906bc33709d3c012d964f
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>