s390x/tcg: fix and cleanup mcck injection

The architecture mode indication wasn't stored. The split of certain
64bit fields was unnecessary. Also, the complete clock comparator, not
just bit 0-55 (starting at byte 1) was stored.

We now generate a proper MCIC via the same helper we use for KVM.

There is more to clean up, but we will change the other parts later on
either way.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20171208160207.26494-3-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
