[SCSI] aic7xxx: fix bug in DT handing

Basically DT isn't reported or handled at all.  The problem is that
lines of code like this:

spi_dt(starget) = tinfo->curr.ppr_options & MSG_EXT_PPR_DT_REQ;

don't do what you think they do when spi_dt is a single bit variable.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/aic7xxx/aic7xxx_osm.c

@@ -1635,9 +1635,9 @@ ahc_send_async(struct ahc_softc *ahc, char channel,
 		spi_period(starget) = tinfo->curr.period;
 		spi_width(starget) = tinfo->curr.width;
 		spi_offset(starget) = tinfo->curr.offset;
-		spi_dt(starget) = tinfo->curr.ppr_options & MSG_EXT_PPR_DT_REQ;
-		spi_qas(starget) = tinfo->curr.ppr_options & MSG_EXT_PPR_QAS_REQ;
-		spi_iu(starget) = tinfo->curr.ppr_options & MSG_EXT_PPR_IU_REQ;
+		spi_dt(starget) = tinfo->curr.ppr_options & MSG_EXT_PPR_DT_REQ ? 1 : 0;
+		spi_qas(starget) = tinfo->curr.ppr_options & MSG_EXT_PPR_QAS_REQ ? 1 : 0;
+		spi_iu(starget) = tinfo->curr.ppr_options & MSG_EXT_PPR_IU_REQ ? 1 : 0;
 		spi_display_xfer_agreement(starget);
 		break;
 	}
@@ -2435,8 +2435,10 @@ static void ahc_linux_set_dt(struct scsi_target *starget, int dt)
 	if (dt) {
 		period = 9;	/* 12.5ns is the only period valid for DT */
 		ppr_options |= MSG_EXT_PPR_DT_REQ;
-	} else if (period == 9)
+	} else if (period == 9) {
 		period = 10;	/* if resetting DT, period must be >= 25ns */
+		ppr_options &= ~MSG_EXT_PPR_DT_REQ;
+	}
 
 	ahc_compile_devinfo(&devinfo, shost->this_id, starget->id, 0,
 			    starget->channel + 'A', ROLE_INITIATOR);