libata: fix build without BMDMA

fix these errors:
drivers/ata/libata-sff.c:2538:3: error: implicit declaration of function
'ata_pci_bmdma_prepare_host'
drivers/ata/libata-sff.c:2549:40: error: 'ata_bmdma_interrupt'
undeclared (first use in this function)

Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-sff.c

@@ -2533,21 +2533,25 @@ static int ata_pci_init_one(struct pci_dev *pdev,
 	if (rc)
 		goto out;
 
+#ifdef CONFIG_ATA_BMDMA
 	if (bmdma)
 		/* prepare and activate BMDMA host */
 		rc = ata_pci_bmdma_prepare_host(pdev, ppi, &host);
 	else
+#endif
 		/* prepare and activate SFF host */
 		rc = ata_pci_sff_prepare_host(pdev, ppi, &host);
 	if (rc)
 		goto out;
 	host->private_data = host_priv;
 	host->flags |= hflags;
 
+#ifdef CONFIG_ATA_BMDMA
 	if (bmdma) {
 		pci_set_master(pdev);
 		rc = ata_pci_sff_activate_host(host, ata_bmdma_interrupt, sht);
 	} else
+#endif
 		rc = ata_pci_sff_activate_host(host, ata_sff_interrupt, sht);
 out:
 	if (rc == 0)