drivers: cpufreq: add interactive cpu governor

This driver adds a dynamic cpufreq policy governor.
Designed for low latency burst workloads.
Scaling it done when coming out of idle instead of polling.

Also, this gets full cpu frequency scaling for workloads
that are latency sensitive, typically interactive workloads.

Signed-off-by: Humberto Borba <humberos@gmail.com>
config: add interactive cpu governor

Signed-off-by: Humberto Borba <humberos@gmail.com>