m68k/mac: Enable PDMA support for PowerBook 190

Stan's tests showed that PDMA improves sequential read performance by
a factor of 5 on a PowerBook 190. Last time I tried this on a
PowerBook 520 it didn't work, so let's not enable it there until
it can be tested with the present mac_scsi driver.
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/mac/config.c

@@ -699,7 +699,7 @@ static struct mac_model mac_data_table[] = {
 		.name		= "PowerBook 190",
 		.adb_type	= MAC_ADB_PB2,
 		.via_type	= MAC_VIA_QUADRA,
-		.scsi_type	= MAC_SCSI_LATE,
+		.scsi_type	= MAC_SCSI_OLD,
 		.ide_type	= MAC_IDE_BABOON,
 		.scc_type	= MAC_SCC_QUADRA,
 		.floppy_type	= MAC_FLOPPY_SWIM_ADDR2,
@@ -1061,9 +1061,7 @@ int __init mac_platform_init(void)
 			mac_scsi_old_rsrc, ARRAY_SIZE(mac_scsi_old_rsrc));
 		break;
 	case MAC_SCSI_LATE:
-		/* PDMA logic in 68040 PowerBooks is somehow different to
-		 * '030 models. It's probably more like Quadras (see mac_esp).
-		 */
+		/* XXX PDMA support for PowerBook 500 series needs testing */
 		platform_device_register_simple("mac_scsi", 0,
 			mac_scsi_late_rsrc, ARRAY_SIZE(mac_scsi_late_rsrc));
 		break;