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>
diff --git a/security/keys/gc.c b/security/keys/gc.c
index 61ab7c8..d67c97b 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -62,7 +62,7 @@
 
 	if (gc_at <= now || test_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags)) {
 		kdebug("IMMEDIATE");
-		queue_work(system_nrt_wq, &key_gc_work);
+		schedule_work(&key_gc_work);
 	} else if (gc_at < key_gc_next_run) {
 		kdebug("DEFERRED");
 		key_gc_next_run = gc_at;
@@ -77,7 +77,7 @@
 void key_schedule_gc_links(void)
 {
 	set_bit(KEY_GC_KEY_EXPIRED, &key_gc_flags);
-	queue_work(system_nrt_wq, &key_gc_work);
+	schedule_work(&key_gc_work);
 }
 
 /*
@@ -120,7 +120,7 @@
 	set_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags);
 
 	kdebug("schedule");
-	queue_work(system_nrt_wq, &key_gc_work);
+	schedule_work(&key_gc_work);
 
 	kdebug("sleep");
 	wait_on_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE, key_gc_wait_bit,
@@ -369,7 +369,7 @@
 	}
 
 	if (gc_state & KEY_GC_REAP_AGAIN)
-		queue_work(system_nrt_wq, &key_gc_work);
+		schedule_work(&key_gc_work);
 	kleave(" [end %x]", gc_state);
 	return;