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-acpi.c

@@ -584,7 +584,7 @@ void ide_acpi_get_timing(ide_hwif_t *hwif)
  * This function executes the _STM ACPI method for the target channel.
  *
  * _STM requires Identify Drive data, which has to passed as an argument.
- * Unfortunately hd_driveid is a mangled version which we can't readily
+ * Unfortunately drive->id is a mangled version which we can't readily
  * use; hence we'll get the information afresh.
  */
 void ide_acpi_push_timing(ide_hwif_t *hwif)
@@ -614,10 +614,10 @@ void ide_acpi_push_timing(ide_hwif_t *hwif)
 	in_params[0].buffer.length = sizeof(struct GTM_buffer);
 	in_params[0].buffer.pointer = (u8 *)&hwif->acpidata->gtm;
 	in_params[1].type = ACPI_TYPE_BUFFER;
-	in_params[1].buffer.length = sizeof(struct hd_driveid);
+	in_params[1].buffer.length = sizeof(ATA_ID_WORDS * 2);
 	in_params[1].buffer.pointer = (u8 *)&master->idbuff;
 	in_params[2].type = ACPI_TYPE_BUFFER;
-	in_params[2].buffer.length = sizeof(struct hd_driveid);
+	in_params[2].buffer.length = sizeof(ATA_ID_WORDS * 2);
 	in_params[2].buffer.pointer = (u8 *)&slave->idbuff;
 	/* Output buffer: _STM has no output */