ide: add short cables support

This patch allows users to override both host and device side cable detection
with "ideX=ata66" kernel parameter.  Thanks to this it should be now possible
to use UDMA > 2 modes on systems (laptops mainly) which use short 40-pin cable
instead of 80-pin one.

Next patches add automatic detection of some systems using short cables.

Changes:

* Rename hwif->udma_four to hwif->cbl and make it u8.

* Convert all existing users accordingly (use ATA_CBL_* defines while at it).  

* Add ATA_CBL_PATA40_SHORT support to ide-iops.c:eighty_ninty_three().

* Use ATA_CBL_PATA40_SHORT for "ideX=ata66" kernel parameter.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Reviewed-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index f0be5f6..92578b6 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -574,7 +574,10 @@
 	ide_hwif_t *hwif = drive->hwif;
 	struct hd_driveid *id = drive->id;
 
-	if (hwif->udma_four == 0)
+	if (hwif->cbl == ATA_CBL_PATA40_SHORT)
+		return 1;
+
+	if (hwif->cbl != ATA_CBL_PATA80)
 		goto no_80w;
 
 	/* Check for SATA but only if we are ATA5 or higher */
@@ -600,7 +603,8 @@
 
 	printk(KERN_WARNING "%s: %s side 80-wire cable detection failed, "
 			    "limiting max speed to UDMA33\n",
-			    drive->name, hwif->udma_four ? "drive" : "host");
+			    drive->name,
+			    hwif->cbl == ATA_CBL_PATA80 ? "drive" : "host");
 
 	drive->udma33_warned = 1;