The arm64 debug monitor initialisation code uses a CPU hotplug notifier
to clear the OS lock when CPUs come online.
This patch converts the code to the new hotplug mechanism.
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
e937dd5782