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>

include/linux/ide.h

@@ -686,6 +686,8 @@ typedef struct hwif_s {
 	u8 mwdma_mask;
 	u8 swdma_mask;
 
+	u8 cbl;		/* cable type */
+
 	hwif_chipset_t chipset;	/* sub-module for tuning.. */
 
 	struct pci_dev  *pci_dev;	/* for pci chipsets */
@@ -792,7 +794,6 @@ typedef struct hwif_s {
 	unsigned	sharing_irq: 1;	/* 1 = sharing irq with another hwif */
 	unsigned	reset      : 1;	/* reset after probe */
 	unsigned	autodma    : 1;	/* auto-attempt using DMA at boot */
-	unsigned	udma_four  : 1;	/* 1=ATA-66 capable, 0=default */
 	unsigned	no_lba48   : 1; /* 1 = cannot do LBA48 */
 	unsigned	no_lba48_dma : 1; /* 1 = cannot do LBA48 DMA */
 	unsigned	auto_poll  : 1; /* supports nop auto-poll */