ide: remove ide_task_t typedef

While at it:
- rename struct ide_task_s to struct ide_cmd
- remove stale comments from idedisk_{read_native,set}_max_address()
- drop unused 'cmd' argument from ide_{cmd,task}_ioctl()
- drop unused 'task' argument from tx4939ide_tf_load_fixup()
- rename ide_complete_task() to ide_complete_cmd()
- use consistent naming for struct ide_cmd variables

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-eh.c

@@ -125,10 +125,10 @@ ide_startstop_t ide_error(ide_drive_t *drive, const char *msg, u8 stat)
 	if (!blk_fs_request(rq)) {
 		rq->errors = 1;
 		if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
-			ide_task_t *task = rq->special;
+			struct ide_cmd *cmd = rq->special;
 
-			if (task)
-				ide_complete_task(drive, task, stat, err);
+			if (cmd)
+				ide_complete_cmd(drive, cmd, stat, err);
 		} else if (blk_pm_request(rq)) {
 			ide_complete_pm_rq(drive, rq);
 			return ide_stopped;