intel_idle: Split up and provide per CPU initialization func

Function split up, should have no functional change.

Provides entry point for physically hotplugged CPUs
to initialize and activate cpuidle.

Signed-off-by: Thomas Renninger <trenn@suse.de>
CC: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
CC: Shaohua Li <shaohua.li@intel.com>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>