fix detecting devices on vt6421 SATA controller
("ATA: abnormal status 0x7F on port 0xB007"):
--- drivers/ata/sata_via.c.tv6	2006-08-20 16:37:41.000000000 +0200
+++ drivers/ata/sata_via.c	2006-08-20 17:20:23.000000000 +0200
@@ -244,7 +244,7 @@
 
 static void vt6421_error_handler(struct ata_port *ap)
 {
-	return ata_bmdma_drive_eh(ap, ata_std_prereset, NULL,
+	return ata_bmdma_drive_eh(ap, vt6420_prereset, ata_std_softreset,
 				  sata_std_hardreset, ata_std_postreset);
 }