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/arm/icside.c b/drivers/ide/arm/icside.c
index df4af40..ca9e8ea 100644
--- a/drivers/ide/arm/icside.c
+++ b/drivers/ide/arm/icside.c
@@ -265,8 +265,8 @@
 	 * If we're going to be doing MW_DMA_1 or MW_DMA_2, we should
 	 * take care to note the values in the ID...
 	 */
-	if (use_dma_info && drive->id->eide_dma_time > cycle_time)
-		cycle_time = drive->id->eide_dma_time;
+	if (use_dma_info && drive->id[ATA_ID_EIDE_DMA_TIME] > cycle_time)
+		cycle_time = drive->id[ATA_ID_EIDE_DMA_TIME];
 
 	drive->drive_data = cycle_time;