workqueue: Increase worker desc's length to 32

workqueue: Increase worker desc's length to 32

Commit 31c89007285d ("workqueue.c: Increase workqueue name length")
increased WQ_NAME_LEN from 24 to 32, but forget to increase
WORKER_DESC_LEN, which would cause truncation when setting kworker's
desc from workqueue_struct's name, process_one_work() for example.

Fixes: 31c89007285d ("workqueue.c: Increase workqueue name length")

Signed-off-by: Wenchao Hao <haowenchao22@gmail.com>
CC: Audra Mitchell <audra@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>