ide: drop "PIO data" argument from ide_get_best_pio_mode()

* Drop no longer needed "PIO data" argument from ide_get_best_pio_mode()
  and convert all users accordingly.

* Remove no longer needed ide_pio_data_t.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/piix.c b/drivers/ide/pci/piix.c
index a4f88d2..41a3612 100644
--- a/drivers/ide/pci/piix.c
+++ b/drivers/ide/pci/piix.c
@@ -219,7 +219,7 @@
  */
 static void piix_tune_drive (ide_drive_t *drive, u8 pio)
 {
-	pio = ide_get_best_pio_mode(drive, pio, 4, NULL);
+	pio = ide_get_best_pio_mode(drive, pio, 4);
 	piix_tune_pio(drive, pio);
 	(void) ide_config_drive_speed(drive, XFER_PIO_0 + pio);
 }