qemu: Move PCI command modelName TypeToString to controller def validate

qemu: Move PCI command modelName TypeToString to controller def validate

Similar to the checking the modelName vs. NAME_NONE, let's make the
ModelNameTypeToString check more generic too within the checking done
in controller validation (with the same ignore certain models.

NB: We need to keep the ModelNameTypeToString fetch in command line
validation since we use it, but at least we can assume it returns
something valid now.