qd65xx: fix PIO mode selection

PIO4 is a maximum PIO mode supported by a driver.  Using "255" as a max_mode
argument to ide_get_best_pio_mode() could result in wrong timings being used
by a driver (for "pio" equal to 5) or OOPS (for "pio" values > 5 && < 255).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Reviewed-by: Alan Cox <alan@lxorguk.ukuu.org.uk>

drivers/ide/legacy/qd65xx.c

@@ -258,8 +258,7 @@ static void qd6580_tune_drive (ide_drive_t *drive, u8 pio)
 	int recovery_time = 415; /* worst case values from the dos driver */
 
 	if (drive->id && !qd_find_disk_type(drive, &active_time, &recovery_time)) {
-		pio = ide_get_best_pio_mode(drive, pio, 255, &d);
-		pio = min_t(u8, pio, 4);
+		pio = ide_get_best_pio_mode(drive, pio, 4, &d);
 
 		switch (pio) {
 			case 0: break;