ide: add struct ide_taskfile (take 2)

* Don't set write-only ide_task_t.hobRegister[6] and ide_task_t.hobRegister[7]
  in idedisk_set_max_address_ext().

* Add struct ide_taskfile and use it in ide_task_t instead of tfRegister[]
  and hobRegister[].

* Remove no longer needed IDE_CONTROL_OFFSET_HOB define.

* Add #ifndef/#endif __KERNEL__ around definitions of {task,hob}_struct_t.

While at it:

* Use ATA_LBA define for LBA bit (0x40) as suggested by Tejun Heo.

v2:
* Add missing newlines. (Noticed by Sergei)

* Use ~ATA_LBA instead of 0xBF. (Noticed by Sergei)

* Use unnamed unions for error/feature and status/command.
  (Suggested by Sergei).

There should be no functionality changes caused by this patch.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Tejun Heo <htejun@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-acpi.c

@@ -388,13 +388,7 @@ static int taskfile_load_raw(ide_drive_t *drive,
 	args.handler      = &task_no_data_intr;
 
 	/* convert gtf to IDE Taskfile */
-	args.tfRegister[1] = gtf->tfa[0];	/* 0x1f1 */
-	args.tfRegister[2] = gtf->tfa[1];	/* 0x1f2 */
-	args.tfRegister[3] = gtf->tfa[2];	/* 0x1f3 */
-	args.tfRegister[4] = gtf->tfa[3];	/* 0x1f4 */
-	args.tfRegister[5] = gtf->tfa[4];	/* 0x1f5 */
-	args.tfRegister[6] = gtf->tfa[5];	/* 0x1f6 */
-	args.tfRegister[7] = gtf->tfa[6];	/* 0x1f7 */
+	memcpy(&args.tf_array[7], &gtf->tfa, 7);
 
 	if (ide_noacpitfs) {
 		DEBPRINT("_GTF execution disabled\n");