core_ctl: Switch isolation to new hotplug state callbacks

Converting the cpu notifier events based core isolation into
registered core ctl isolation hotplug state callbacks as per
new state based cpu hotplug framework.

Change-Id: Ibe918fbd6caf1678ffe12e99fa38fd5e60c3fb7b
Signed-off-by: Sabyasachi Singh <sssingh@codeaurora.org>