RDMA: Update workqueue usage

* ib_wq is added, which is used as the common workqueue for infiniband
  instead of the system workqueue.  All system workqueue usages
  including flush_scheduled_work() callers are converted to use and
  flush ib_wq.

* cancel_delayed_work() + flush_scheduled_work() converted to
  cancel_delayed_work_sync().

* qib_wq is removed and ib_wq is used instead.

This is to prepare for deprecation of flush_scheduled_work().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/qib/qib_qsfp.c b/drivers/infiniband/hw/qib/qib_qsfp.c
index 35b3604..3374a52 100644
--- a/drivers/infiniband/hw/qib/qib_qsfp.c
+++ b/drivers/infiniband/hw/qib/qib_qsfp.c
@@ -485,7 +485,7 @@
 		goto bail;
 	/* We see a module, but it may be unwise to look yet. Just schedule */
 	qd->t_insert = get_jiffies_64();
-	schedule_work(&qd->work);
+	queue_work(ib_wq, &qd->work);
 bail:
 	return;
 }
@@ -493,10 +493,9 @@
 void qib_qsfp_deinit(struct qib_qsfp_data *qd)
 {
 	/*
-	 * There is nothing to do here for now.  our
-	 * work is scheduled with schedule_work(), and
-	 * flush_scheduled_work() from remove_one will
-	 * block until all work ssetup with schedule_work()
+	 * There is nothing to do here for now.  our work is scheduled
+	 * with queue_work(), and flush_workqueue() from remove_one
+	 * will block until all work setup with queue_work()
 	 * completes.
 	 */
 }