[PATCH] workqueue: update kerneldoc

This patch (as812) changes the kerneldoc comments explaining the return
values from queue_work(), queue_delayed_work(), and
queue_delayed_work_on().  The updated comments explain more accurately the
meaning of the return code and avoid suggesting that a 0 value means the
routine was unsuccessful.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>