The tests prefixed default-video* were enabled only for the xml2xml
testing and used impossible configurations.

Enable them for xml2argv testing fix them:
1) aarch64: remove pointless cpu mode
2) s390x: remove pointless cpu and use existing machine type
3) riscv: remove pointless cpu
4) x86: remove pointless cpu and use existing machine type
5) ppc65: use correct machine type and enable USB
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>