While virDomainCapsCPUModel structure contains 'usable' field with
virDomainCapsCPUUsable type, the lower level structure specific to QEMU
driver used virTriStateBool for the same thing and we had to translate
between them.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>