ide: add ide_dev_has_iordy() helper (take 4)

* Add ide_dev_has_iordy() helper and use it sl82c105 host driver.

* Remove no longer needed ide_pio_data_t.use_iordy field.

v2/v3:
* Fix issues noticed by Sergei:
  - correct patch description
  - fix comment in ide_get_best_pio_mode()

v4:
* Fix "ata_" prefix (Noticed by Jeff).

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-lib.c b/drivers/ide/ide-lib.c
index d45bbad..d5cc96b 100644
--- a/drivers/ide/ide-lib.c
+++ b/drivers/ide/ide-lib.c
@@ -267,18 +267,15 @@
 {
 	int pio_mode;
 	int cycle_time = 0;
-	int use_iordy = 0;
 	struct hd_driveid* id = drive->id;
 	int overridden  = 0;
 
 	if (mode_wanted != 255) {
 		pio_mode = mode_wanted;
-		use_iordy = (pio_mode > 2);
 	} else if (!drive->id) {
 		pio_mode = 0;
 	} else if ((pio_mode = ide_scan_pio_blacklist(id->model)) != -1) {
 		printk(KERN_INFO "%s: is on PIO blacklist\n", drive->name);
-		use_iordy = (pio_mode > 2);
 	} else {
 		pio_mode = id->tPIO;
 		if (pio_mode > 2) {	/* 2 is maximum allowed tPIO value */
@@ -286,8 +283,7 @@
 			overridden = 1;
 		}
 		if (id->field_valid & 2) {	  /* drive implements ATA2? */
-			if (id->capability & 8) { /* drive supports use_iordy? */
-				use_iordy = 1;
+			if (id->capability & 8) { /* IORDY supported? */
 				cycle_time = id->eide_pio_iordy;
 				if (id->eide_pio_modes & 7) {
 					overridden = 0;
@@ -325,7 +321,6 @@
 	if (d) {
 		d->pio_mode = pio_mode;
 		d->cycle_time = cycle_time ? cycle_time : ide_pio_timings[pio_mode].cycle_time;
-		d->use_iordy = use_iordy;
 	}
 	return pio_mode;
 }