s390x/cpumodel: default enable mepoch for z14 and later

s390x/cpumodel: default enable mepoch for z14 and later

Latest systems and host kernels support mepoch, which is a
feature that was meant to be supported for z14 GA1 from the
get-go. Let's copy it to the z14 GA1 default CPU model.

Machines s390-ccw-virtio-3.1 and older will retain the old CPU
models and will not provide this bit nor the extended PTFF
functions in the default model.

Signed-off-by: Collin Walling <walling@linux.ibm.com>
Message-Id: <20190212011657.18324-2-walling@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>