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>
diff --git a/drivers/ide/pci/pdc202xx_old.c b/drivers/ide/pci/pdc202xx_old.c
index de9a274..23e861b 100644
--- a/drivers/ide/pci/pdc202xx_old.c
+++ b/drivers/ide/pci/pdc202xx_old.c
@@ -86,7 +86,7 @@
 		 * Prefetch_EN / IORDY_EN / PA[3:0] bits of register A
 		 */
 		AP &= ~0x3f;
-		if (drive->id->capability & 4)
+		if (drive->driveid->capability & 4)
 			AP |= 0x20;	/* set IORDY_EN bit */
 		if (drive->media == ide_disk)
 			AP |= 0x10;	/* set Prefetch_EN bit */
@@ -154,10 +154,10 @@
 
 static void pdc202xx_quirkproc(ide_drive_t *drive)
 {
-	const char **list, *model = drive->id->model;
+	const char **list, *m = (char *)&drive->id[ATA_ID_PROD];
 
 	for (list = pdc_quirk_drives; *list != NULL; list++)
-		if (strstr(model, *list) != NULL) {
+		if (strstr(m, *list) != NULL) {
 			drive->quirk_list = 2;
 			return;
 		}