auto_hotplug: enable the min_online_cpus value
Use a module_param_cb to set the minimum number of online CPUs when the screen is on.

The values are between 1-4.

usage:
echo '1' > /sys/module/auto_hotplug/parameters/min_online_cpus
auto_hotplug: some tweaks
Several tweaks to try to improve battery life.
Add max_online_cpus feature
Fix up some various naming issues after inclusion of max_online_cpus code
Francisco is right, onlining all cores is a nice workaround for the real problem.
Onlining all cores using the driver's framework.
Some whitespace cleanup.