Need better test coverage for `usbdrvce`

I found an optimization for `usbdrvce`

https://github.com/CE-Programming/toolchain/commit/c50e7f97e548c295b5f4b74097895e02b2bcc541

However, I realized that my optimization has a bug. It was supposed to be `jq z,.unknown_transfer`, not `jq nz,.unknown_transfer`, but all tests passed either way.