ide: make drive->id an union (take 2)

Make drive->id an unnamed union so id can be accessed either by using
'u16 *id' or 'struct hd_driveid *driveid'.  Then convert all existing
drive->id users accordingly (using 'u16 *id' when possible).

This is an intermediate step to make ide 'struct hd_driveid'-free.

While at it:

- Add missing KERN_CONTs in it821x.c.

- Use ATA_ID_WORDS and ATA_ID_*_LEN defines.

- Remove unnecessary checks for drive->id.

- s/drive_table/table/ in ide_in_drive_list().

- Cleanup ide_config_drive_speed() a bit.

- s/drive1/dev1/ & s/drive0/dev0/ in ide_undecoded_slave().

v2:
Fix typo in drivers/ide/ppc/pmac.c. (From Stephen Rothwell)

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-taskfile.c

@@ -729,7 +729,7 @@ int ide_cmd_ioctl (ide_drive_t *drive, unsigned int cmd, unsigned long arg)
 	u8 args[4], xfer_rate = 0;
 	ide_task_t tfargs;
 	struct ide_taskfile *tf = &tfargs.tf;
-	struct hd_driveid *id = drive->id;
+	u16 *id = drive->id;
 
 	if (NULL == (void *) arg) {
 		struct request *rq;
@@ -772,7 +772,9 @@ int ide_cmd_ioctl (ide_drive_t *drive, unsigned int cmd, unsigned long arg)
 	if (tf->command == WIN_SETFEATURES &&
 	    tf->feature == SETFEATURES_XFER &&
 	    tf->nsect >= XFER_SW_DMA_0 &&
-	    (id->dma_ultra || id->dma_mword || id->dma_1word)) {
+	    (id[ATA_ID_UDMA_MODES] ||
+	     id[ATA_ID_MWDMA_MODES] ||
+	     id[ATA_ID_SWDMA_MODES])) {
 		xfer_rate = args[1];
 		if (tf->nsect > XFER_UDMA_2 && !eighty_ninty_three(drive)) {
 			printk(KERN_WARNING "%s: UDMA speeds >UDMA33 cannot "