Currently the hotplug notifier is registered in device init. This is
too late to handle events at early SMP boot stage. Later upstream code
(around 4.10) changes this, but relies on the work done to make the
whole CPU hotplug code a state machine.

CVE-2018-3620
CVE-2018-3646
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>