cpu/hotplug: Fix some cpuhp->target issues
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2086305
Tested: By me with the reproducer and several days of cpu hot[un]plug
stressing.
Fix a couple of issues with the handling of cpuhp->target. These
are now in upstream Linux.
Signed-off-by: Phil Auld pauld@redhat.com