libata-link: linkify reset

Make reset methods and related functions deal with ata_link instead of
ata_port.

* ata_do_reset()
* ata_eh_reset()
* all prereset/reset/postreset methods and related functions

This patch introduces no behavior change.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/ata_piix.c b/drivers/ata/ata_piix.c
index 92c2d50..03fe493 100644
--- a/drivers/ata/ata_piix.c
+++ b/drivers/ata/ata_piix.c
@@ -657,19 +657,20 @@
 
 /**
  *	piix_pata_prereset - prereset for PATA host controller
- *	@ap: Target port
+ *	@link: Target link
  *	@deadline: deadline jiffies for the operation
  *
  *	LOCKING:
  *	None (inherited from caller).
  */
-static int piix_pata_prereset(struct ata_port *ap, unsigned long deadline)
+static int piix_pata_prereset(struct ata_link *link, unsigned long deadline)
 {
+	struct ata_port *ap = link->ap;
 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
 
 	if (!pci_test_config_bits(pdev, &piix_enable_bits[ap->port_no]))
 		return -ENOENT;
-	return ata_std_prereset(ap, deadline);
+	return ata_std_prereset(link, deadline);
 }
 
 static void piix_pata_error_handler(struct ata_port *ap)