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/ide-timings.c b/drivers/ide/ide-timings.c
index 8c2f832..d64f345 100644
--- a/drivers/ide/ide-timings.c
+++ b/drivers/ide/ide-timings.c
@@ -78,15 +78,15 @@
 
 u16 ide_pio_cycle_time(ide_drive_t *drive, u8 pio)
 {
-	struct hd_driveid *id = drive->id;
+	u16 *id = drive->id;
 	struct ide_timing *t = ide_timing_find_mode(XFER_PIO_0 + pio);
 	u16 cycle = 0;
 
-	if (id->field_valid & 2) {
-		if (id->capability & 8)
-			cycle = id->eide_pio_iordy;
+	if (id[ATA_ID_FIELD_VALID] & 2) {
+		if (drive->driveid->capability & 8)
+			cycle = id[ATA_ID_EIDE_PIO_IORDY];
 		else
-			cycle = id->eide_pio;
+			cycle = id[ATA_ID_EIDE_PIO];
 
 		/* conservative "downgrade" for all pre-ATA2 drives */
 		if (pio < 3 && cycle < t->cycle)
@@ -138,7 +138,7 @@
 int ide_timing_compute(ide_drive_t *drive, u8 speed,
 		       struct ide_timing *t, int T, int UT)
 {
-	struct hd_driveid *id = drive->id;
+	u16 *id = drive->id;
 	struct ide_timing *s, p;
 
 	/*
@@ -157,16 +157,15 @@
 	 * If the drive is an EIDE drive, it can tell us it needs extended
 	 * PIO/MWDMA cycle timing.
 	 */
-	if (id && id->field_valid & 2) {	/* EIDE drive */
-
+	if (id[ATA_ID_FIELD_VALID] & 2) {	/* EIDE drive */
 		memset(&p, 0, sizeof(p));
 
 		if (speed <= XFER_PIO_2)
-			p.cycle = p.cyc8b = id->eide_pio;
+			p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO];
 		else if (speed <= XFER_PIO_5)
-			p.cycle = p.cyc8b = id->eide_pio_iordy;
+			p.cycle = p.cyc8b = id[ATA_ID_EIDE_PIO_IORDY];
 		else if (speed >= XFER_MW_DMA_0 && speed <= XFER_MW_DMA_2)
-			p.cycle = id->eide_dma_min;
+			p.cycle = id[ATA_ID_EIDE_DMA_MIN];
 
 		ide_timing_merge(&p, t, t, IDE_TIMING_CYCLE | IDE_TIMING_CYC8B);
 	}