libata: implement ata_host_detach()

Implement ata_host_detach() which calls ata_port_detach() for each
port in the host and export it.  ata_port_detach() is now internal and
thus un-exported.  ata_host_detach() will be used as the 'deregister
from libata layer' function after devres conversion.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/include/linux/libata.h b/include/linux/libata.h
index a2458df..e9a0cfd 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -719,7 +719,7 @@
 extern int ata_pci_clear_simplex(struct pci_dev *pdev);
 #endif /* CONFIG_PCI */
 extern int ata_device_add(const struct ata_probe_ent *ent);
-extern void ata_port_detach(struct ata_port *ap);
+extern void ata_host_detach(struct ata_host *host);
 extern void ata_host_init(struct ata_host *, struct device *,
 			  unsigned long, const struct ata_port_operations *);
 extern void ata_host_remove(struct ata_host *host);