workqueue: deprecate __cancel_delayed_work()

Now that cancel_delayed_work() can be safely called from IRQ handlers,
there's no reason to use __cancel_delayed_work().  Use
cancel_delayed_work() instead of __cancel_delayed_work() and mark the
latter deprecated.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Roland Dreier <roland@kernel.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/dsi.c

@@ -4306,7 +4306,7 @@ static void dsi_framedone_irq_callback(void *data, u32 mask)
 	 * and is sending the data.
 	 */
 
-	__cancel_delayed_work(&dsi->framedone_timeout_work);
+	cancel_delayed_work(&dsi->framedone_timeout_work);
 
 	dsi_handle_framedone(dsidev, 0);
 }