Fix hybrid CPU core pinning

[patatahooligan]

Previously the condition would always evaluate to false. With the fix any core with >=95% of max_freq will be added to the set of cores to keep.

I tested this on my system with a 13600k by comparing the results of running a make -j20 job with and without gamemode. With gamemode I saw the expected results, namely:

• only the first 12 cores showing significant usage with the rest being close to 0%.
• taskset -ap $PID returning fff for the make process, instead of the default fffff.

Fixes #451.