workqueue: deprecate system_nrt[_freezable]_wq

system_nrt[_freezable]_wq are now spurious.  Mark them deprecated and
convert all users to system[_freezable]_wq.

If you're cc'd and wondering what's going on: Now all workqueues are
non-reentrant, so there's no reason to use system_nrt[_freezable]_wq.
Please use system[_freezable]_wq instead.

This patch doesn't make any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-By: Lai Jiangshan <laijs@cn.fujitsu.com>

Cc: Jens Axboe <axboe@kernel.dk>
Cc: David Airlie <airlied@linux.ie>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>

drivers/hid/hid-wiimote-ext.c

@@ -204,7 +204,7 @@ static void wiiext_worker(struct work_struct *work)
 /* schedule work only once, otherwise mark for reschedule */
 static void wiiext_schedule(struct wiimote_ext *ext)
 {
-	queue_work(system_nrt_wq, &ext->worker);
+	schedule_work(&ext->worker);
 }
 
 /*