[SCSI] tgt: fix build errors when dprintk is defined

drivers/scsi/ibmvscsi/ibmvstgt.c: In function 'ibmvstgt_cmd_done':
drivers/scsi/ibmvscsi/ibmvstgt.c:292: error: 'cmd' undeclared (first use in this function)
drivers/scsi/ibmvscsi/ibmvstgt.c:292: error: (Each undeclared identifier is reported only once
drivers/scsi/ibmvscsi/ibmvstgt.c:292: error: for each function it appears in.)

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/ibmvscsi/ibmvstgt.c

@@ -290,7 +290,7 @@ static int ibmvstgt_cmd_done(struct scsi_cmnd *sc,
 	int err = 0;
 
 	dprintk("%p %p %x %u\n", iue, target, vio_iu(iue)->srp.cmd.cdb[0],
-		cmd->usg_sg);
+		scsi_sg_count(sc));
 
 	if (scsi_sg_count(sc))
 		err = srp_transfer_data(sc, &vio_iu(iue)->srp.cmd, ibmvstgt_rdma, 1, 1);