ANDROID: cpu/hotplug: create vendor hook for cpu_up/cpu_down

Include a vendor hook for cpu_up and cpu_down to force the
rebuilding of scheduling domains prior to issuing a new
cpu up/down.  Include a Kernel Export for
cpuset_wait_for_hotplug such that vendor hooks may refer
to this functionality, to ensure scheduling domains are
complete.

Bug: 176152285
Change-Id: I778dbc5e4f9d613f39b8c61f244c0f33020a3dd3
Signed-off-by: Stephen Dickey <dickey@codeaurora.org>