Because this config is not yet upstreamed (pending arm64/bhyve/vmm
actually landing in main), we have to maintain our own for the time
being.
Tweak the config to work around two problems which arose after the
latest update:
- EFI support implies SMBIOS support, which requires that we implement a finalizer, which we don't have. Since SMBIOS support isn't required, just remove it.
- Don't configure EVENT, as we don't use it, and its configuration implies that we implement a hook that runs immediately before command processing.