qcom: core_ctl_helper: Add wrapper for CPU hotplug

Different kernel version needs to use different kernel APIs for
hotplug. Add wrapper for CPU hotplug so that external module can be
used across different kernel releases.

Use device_online/offline() API for CPU hotplug.

Change-Id: Id21855f4ddc62bc9e9e6b45a856c245fd18d1514
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>