qcom: hyp_core_ctl: Handle CPU offline case after CPU is dead

A CPU can't be left in isolated state while it is offline. The
scheduler provides sched_unisolate_cpu_unlocked() API to un-isolate
a CPU while it is going offline. Currently we are calling this API
from CPUHP_AP_ONLINE_DYN callback which gets called before the CPU
is marked offline. Because of this CPU comes out of isolation state
and soon after enters offline state. To avoid, this register for a
callback that gets invoked after CPU is dead.

Also use nocalls() version for hotplug callbacks, Since this driver
state machine is kicked from the user space and there is no need for
the hotplug notifications during driver's initialization.

Change-Id: I7eb4af2f0784f12fd314096fe23dc7600ef9094c
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>