drivers: cpufreq: add support for scaling available frequencies

this patch implements sysfs for scaling
between available cpu frequencies

also, it sets a safe limits during boot process

min: 200MHz
max: 1400|1600MHz

This change reverts this patch
https://gerrit.omnirom.org/#/c/5685/

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: Ia424ee5fd125a9d45839091d8bd7057b8e560c15
[WIP] exynos-hotplug: Disable dynamic hotplug when governor is hotplug-aware

So far this is only implemented for dynamic-dvfs-nr_running hotplug
but we need it for all algorithms we might use on 4412.

The "indpendent" hotplug drivers will conflict with hotplug-aware
CPU governors, so we disable the "independent" hotplug driver
when the governor is changed to a hotplugging-aware one.

Change-Id: Idce21af0e10e62e1633e5c9308b17a207ae2f4bb