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/pci/tc86c001.c b/drivers/ide/pci/tc86c001.c
index cee619b..8de1f8e 100644
--- a/drivers/ide/pci/tc86c001.c
+++ b/drivers/ide/pci/tc86c001.c
@@ -220,13 +220,13 @@
 	hwif->ide_dma_check	= &tc86c001_config_drive_xfer_rate;
 	hwif->dma_start 	= &tc86c001_dma_start;
 
-	if (!hwif->udma_four) {
+	if (hwif->cbl != ATA_CBL_PATA40_SHORT) {
 		/*
 		 * System Control  1 Register bit 13 (PDIAGN):
 		 * 0=80-pin cable, 1=40-pin cable
 		 */
 		scr1 = hwif->INW(sc_base + 0x00);
-		hwif->udma_four = (scr1 & 0x2000) ? 0 : 1;
+		hwif->cbl = (scr1 & 0x2000) ? ATA_CBL_PATA40 : ATA_CBL_PATA80;
 	}
 
 	if (!noautodma)