workqueue: Update cpumasks after only applying it successfully

Make workqueue_unbound_exclude_cpumask() and workqueue_set_unbound_cpumask()
only update wq_isolated_cpumask and wq_requested_unbound_cpumask when
workqueue_apply_unbound_cpumask() returns successfully.

Fixes: fe28f631("workqueue: Add workqueue_unbound_exclude_cpumask() to exclude CPUs from wq_unbound_cpumask")
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Tejun Heo <tj@kernel.org>