This element is not always present, see e.g.
x86_64-cpuid-Xeon-X5460-host.xml, x86_64-cpuid-Pentium-P6100-host.xml,
or x86_64-cpuid-EPYC-7601-32-Core-ibpb-host.xml.
Signed-off-by: Tim Wiederhake <twiederh@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>