make freezeable workqueues singlethread

It is a known fact that freezeable multithreaded workqueues doesn't like
CPU_DEAD. We keep them only for the incoming CPU-hotplug rework.

Sadly, we can't just kill create_freezeable_workqueue() right now, make
them singlethread.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/workqueue.h

@@ -122,7 +122,7 @@ extern struct workqueue_struct *__create_workqueue(const char *name,
 						    int singlethread,
 						    int freezeable);
 #define create_workqueue(name) __create_workqueue((name), 0, 0)
-#define create_freezeable_workqueue(name) __create_workqueue((name), 0, 1)
+#define create_freezeable_workqueue(name) __create_workqueue((name), 1, 1)
 #define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0)
 
 extern void destroy_workqueue(struct workqueue_struct *wq);