How to enable experimental CPU frequency support

[John Walicki]

In Peter's blog post (1), he mentions that there now experimental CPU frequency
support for the Raspberry Pi.

I can't get my Raspberry Pi 3 B+ to scale beyond 600MHz.   How do I enable the
experimental CPU frequency support in /boot/efi/config.txt ?

I'm running Fedora 29 4.19.10-300 kernel.  Thanks!
-- John

(1) - https://nullr0ute.com/2018/12/raspberry-pi-improvements-in-fedora-29/