scsi/osd: don't save block errors into req_results

We will only have sense data if the command executed and got a SCSI
result, so this is pointless.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>