scsi: sd: Remove a superfluous assignment
Since blk_rq_bytes(req) returns req->__data_len, assigning that value to
req->__data_len is superfluous. Hence remove that assignment.
See also commit 5db44863b6eb ("[SCSI] sd: Implement support for WRITE SAME").
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>