scsi: sg: remove bad blk_end_request_all() call

We just need to free the request here. Additionally, this is currently
wrong for a queue that's using MQ currently, it'll crash.

Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>