cpufreq: interactive: Add target_loads_down freq selection

Using a single set of target loads causes an excessive number
of frequency changes.  Reduce by having a mode that allows
for separate load factos for "up" frequency selection and
"down" frequency selection.

If user-space specifies target_loads_down then the new
duel mode frequency selection will be used and frequencies
will be scaled up to meet the load requirements but they
will only be scaled down if the can be scaled down without
violating the down target loads.

If user-space does not store a value in target_loads_down
then this change makes no functional difference in the
governor.

Change-Id: I79e9b4b203f7dc9f24d7bb250881ffee26b863ce