msm: pm2: Support HOTPLUG functionality for non boot CPU's

In a multicore environment one of the CPU acts as a master
and rest all will be treated as non-boot CPU's. When the
hotplug happens non-boot CPU's are logically removed from
the kernel. But these cores still draw some power.

These changes will put the core into low power mode when they
are hotplugged. This will minimise the power consumption.

Change-Id: Ia0a54818df08efc48b68558c4325abd913800a26
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>