libata: Add helper ata_shost_to_port()
diff --git a/drivers/scsi/sata_svw.c b/drivers/scsi/sata_svw.c
index e15c693..d5eb537 100644
--- a/drivers/scsi/sata_svw.c
+++ b/drivers/scsi/sata_svw.c
@@ -257,7 +257,7 @@
 	int len, index;
 
 	/* Find  the ata_port */
-	ap = (struct ata_port *) &shost->hostdata[0];
+	ap = ata_shost_to_port(shost);
 	if (ap == NULL)
 		return 0;