Q800 Emulation uses the wrong VirtIO device

[adespoton]

Describe the issue
When emulating the Quadra 800 via qemu-system-ppc, features such as file sharing, the tablet driver (that allows for automatic mouse capture/release), networking, audio and mounting of Mini vMac/Basilisk II/SheepShaver disk images fails because UTM attempts to load virtio-pci instead of nubus-virtio-mmio as outlined in https://www.emaculation.com/forum/viewtopic.php?t=12059 .
This means that to boot a Quadra 800 UTM configuration, all these features must first be disabled/removed and will not be available to the user.

To fix this, the configuration for Quadra 800 hardware will need to default to NuBus devices instead of PCI devices. Also, UTM will need to include the declrom image from https://github.com/elliotnunn/classicvirtio/releases/tag/latest, as this does not appear to be available alongside QEMU in the 4.6.3 build of UTM.

Configuration

• UTM Version: 4.6.3
• macOS Version: 15.1.1
• Mac Chip (Intel, M1, ...): M1