u8500_hotplug: add load-based hotplugging

Also only update cpufreq policy on suspend. Refactored a bit of the suspend/resume operations.

This code is a little messy right now, will clean up soon.

Change-Id: Icd54a01ee6e6fac9fdb8e5c59d8b1b22a55802f3
Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>