libata-sff: add ata_sff_queue_work() & ata_sff_queue_delayed_work()

This patch adds ata_sff_queue_work() & ata_sff_queue_delayed_work() routine in
libata-sff.c file. This routine can be used by ata drivers to use ata_sff_wq.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 71333aa..c71f469 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1610,6 +1610,9 @@
 extern void ata_sff_irq_clear(struct ata_port *ap);
 extern int ata_sff_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
 			    u8 status, int in_wq);
+extern void ata_sff_queue_work(struct work_struct *work);
+extern void ata_sff_queue_delayed_work(struct delayed_work *dwork,
+		unsigned long delay);
 extern void ata_sff_queue_pio_task(struct ata_link *link, unsigned long delay);
 extern unsigned int ata_sff_qc_issue(struct ata_queued_cmd *qc);
 extern bool ata_sff_qc_fill_rtf(struct ata_queued_cmd *qc);