workqueue: Let DISASSOCIATED workers follow unbound wq cpumask changes

workqueue: Let DISASSOCIATED workers follow unbound wq cpumask changes

When workqueue cpumask changes are committed, the DISASSOCIATED workers
affinity is not touched and this might be a problem down the line for
isolated setups when the DISASSOCIATED pools still have works to run
after the cpu is offline.

Make sure the workers' affinity is updated every time a workqueue cpumask
changes, so these workers can't break isolation.

Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Tejun Heo <tj@kernel.org>