workqueue.c: Increase workqueue name length

Currently we limit the size of the workqueue name to 24 characters due to
commit ecf6881f

 ("workqueue: make workqueue->name[] fixed len")
Increase the size to 32 characters and print a warning in the event
the requested name is larger than the limit of 32 characters.

Signed-off-by: Audra Mitchell <audra@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>