Support for virtio devices

[s-macke]

Once the virtio interface is finished (look at the other issue) we need support for the following the devices:
virtio-network
virtio-console
virtio-block
virtio-pci (not sure, if this would work)

[s-macke]

A lot of virtio devices are implemented, but not acticvated yet. Even initial support for virtio-gpu.
I will switch when I update the kernel. Hopefully it will also work for riscv. But riscv does not support mmio.