qemumonitorjsontest: AddNetdev: Use real variant
qemumonitorjsontest: AddNetdev: Use real variant

QEMU now formalized the arguments of netdev-add in the schema, so we
must use a real type to pass the schema validation once the schema is
updated.

The 'user' variant doesn't have any other mandatory fields.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

zippy2/libvirt,crobinso/libvirt,crobinso/libvirt,libvirt/libvirt,libvirt/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,olafhering/libvirt,jardasgit/libvirt,libvirt/libvirt,nertpinx/libvirt,crobinso/libvirt,libvirt/libvirt,olafhering/libvirt,nertpinx/libvirt,jardasgit/libvirt,zippy2/libvirt,nertpinx/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,crobinso/libvirt,zippy2/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,zippy2/libvirt,olafhering/libvirt,jfehlig/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,nertpinx/libvirt,olafhering/libvirt