ht6560b can only do up to PIO mode 4

According to the datasheet, ht6560b only supports up to PIO mode 4.

[bart: manually ported it over 2.6.25-rc2]

Signed-off-by: Jan Evert van Grootheest <janevert@caiway.nl>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/legacy/ht6560b.c b/drivers/ide/legacy/ht6560b.c
index 02d12c7..2701e7d 100644
--- a/drivers/ide/legacy/ht6560b.c
+++ b/drivers/ide/legacy/ht6560b.c
@@ -323,7 +323,7 @@
 				  IDE_HFLAG_NO_DMA |
 				  IDE_HFLAG_NO_AUTOTUNE |
 				  IDE_HFLAG_ABUSE_PREFETCH,
-	.pio_mask		= ATA_PIO5,
+	.pio_mask		= ATA_PIO4,
 };
 
 static int __init ht6560b_init(void)