mhz: add new package

mhz: add new package

mhz is a tool for mathematically calculating the current CPU frequency, it
has proven to be a really good help while developing CPU frequency scaling
solutions as it allows to independently prove that scaling actually works.

Now that the author has added a license we can package it for the all to
use.

Signed-off-by: Robert Marko <robimarko@gmail.com>
(cherry picked from commit 89123b308f98de6e6e77a1bf21586c8fafc83413)