[PATCH] libata: move ata_irq_on() into libata-sff.c

ata_irq_on() isn't used outside of libata core layer.  The function is
TF/SFF interface specific but currently used by core path with some
hack too.  Move it from include/linux/libata.h to
drivers/ata/libata-sff.c.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 0ed263b..c833000 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -120,4 +120,7 @@
 extern void ata_port_wait_eh(struct ata_port *ap);
 extern void ata_qc_schedule_eh(struct ata_queued_cmd *qc);
 
+/* libata-sff.c */
+extern u8 ata_irq_on(struct ata_port *ap);
+
 #endif /* __LIBATA_H__ */