core_ctl: Harden the adjustment_possible() check for unisolation

When the need for CPUs is more than the active CPUs and there are some
isolated CPUs, we wakeup the core_ctl thread to unisolate some CPUs.
The core_ctl task can't unisolate any CPU if all of them are isolated
by other clients. Track the number of isolated CPUs by core_ctl and
wakeup the core_ctl task when adjustment is really possible.

Change-Id: I3ce5254d0c0f50b86b5ac504fe607b8aa585284a
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>