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>
diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index b593814..dc3fd1e 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -2004,7 +2004,7 @@
 	unsigned long delay;
 
 	if (list_empty(&mad_agent_priv->wait_list)) {
-		__cancel_delayed_work(&mad_agent_priv->timed_work);
+		cancel_delayed_work(&mad_agent_priv->timed_work);
 	} else {
 		mad_send_wr = list_entry(mad_agent_priv->wait_list.next,
 					 struct ib_mad_send_wr_private,