[SCSI] tgt: convert to use the data buffer accessors

- convert to use the new accessors for the sg lists and the
parameters.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/scsi_tgt_if.c b/drivers/scsi/scsi_tgt_if.c
index 9815a1a..d2557db 100644
--- a/drivers/scsi/scsi_tgt_if.c
+++ b/drivers/scsi/scsi_tgt_if.c
@@ -112,7 +112,7 @@
 	memset(&ev, 0, sizeof(ev));
 	ev.p.cmd_req.host_no = shost->host_no;
 	ev.p.cmd_req.itn_id = itn_id;
-	ev.p.cmd_req.data_len = cmd->request_bufflen;
+	ev.p.cmd_req.data_len = scsi_bufflen(cmd);
 	memcpy(ev.p.cmd_req.scb, cmd->cmnd, sizeof(ev.p.cmd_req.scb));
 	memcpy(ev.p.cmd_req.lun, lun, sizeof(ev.p.cmd_req.lun));
 	ev.p.cmd_req.attribute = cmd->tag;