libata-sff: ap->[last_]ctl are SFF specific

ap->[last_]ctl are specific to SFF controllers.  Put them inside
CONFIG_ATA_SFF and move initialization into ata_sff_port_init().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-sff.c

@@ -3074,6 +3074,8 @@ EXPORT_SYMBOL_GPL(ata_pci_bmdma_init);
  */
 void ata_sff_port_init(struct ata_port *ap)
 {
+	ap->ctl = ATA_DEVCTL_OBS;
+	ap->last_ctl = 0xFF;
 }
 
 int __init ata_sff_init(void)