libata-sff: kill unused prototype and make ata_dev_select() static

ata_irq_on() was renamed to ata_sff_irq_on() and exported a while ago
but prototype for the original function lingered in
drivers/ata/libata.h.  Kill it.  Also, ata_dev_select() is only used
inside drivers/ata/libata-sff.c.  Make it static.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-sff.c

@@ -511,7 +511,7 @@ EXPORT_SYMBOL_GPL(ata_sff_dev_select);
  *	LOCKING:
  *	caller.
  */
-void ata_dev_select(struct ata_port *ap, unsigned int device,
+static void ata_dev_select(struct ata_port *ap, unsigned int device,
 			   unsigned int wait, unsigned int can_sleep)
 {
 	if (ata_msg_probe(ap))

drivers/ata/libata.h

@@ -202,9 +202,6 @@ static inline int sata_pmp_attach(struct ata_device *dev)
 
 /* libata-sff.c */
 #ifdef CONFIG_ATA_SFF
-extern void ata_dev_select(struct ata_port *ap, unsigned int device,
-                           unsigned int wait, unsigned int can_sleep);
-extern u8 ata_irq_on(struct ata_port *ap);
 extern void ata_pio_task(struct work_struct *work);
 #endif /* CONFIG_ATA_SFF */