Disable usage config

[junetried]

I'm having an issue where my GPU fan will spike to very high speeds and back down for no obvious reason, even when the screen is off and I'm away from the computer. I traced it to the usage config, and found other people describing the same issue, but I couldn't find a way to actually resolve this. At the moment, I've set the usage config to a static value, which has no annoying fan ramping up and down but does allow the GPU to build much more heat than it ought to.

Removing all [[usage_matrix]] entries from mapping.toml doesn't actually seem to disable the usage config, because it still ramps very high sometimes.