qdev: Remove most legacy printers Their functionality is either aesthetic only (e.g. on/off vs. true/false) or obtained by the "human mode" of StringOutputVisitor. Reviewed-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Andreas Färber <afaerber@suse.de>