scsi: ufs: clear UTRD, UPIU req and rsp before new transfers

Clear the UFS data structures before sending new request.

The SCSI command is sent to the device within the UFS UPIU request.
As part of the transfer UPIU preparation, the SCSI command is copied
to the UPIU structure according to the SCSI command size.
As different SCSI commands differ in size from each other, we need
to clear the whole SCSI command field to prevent sending uninitialized
data to the device.

The UPIU response doesn't always include the sense data and can differ
in size.
Hence, the UPIU response should also be cleared before the transfer.

Change-Id: I9bba619dc884e973a05566e0f975bd8473612644
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>