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: I04fa336cc51b535d98c8de8246a643bafb60f73f
Signed-off-by: Sabyasachi Singh <sssingh@codeaurora.org>
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>