s390x/cpu_models: make "max" match the unmodified "qemu" CPU model under TCG

s390x/cpu_models: make "max" match the unmodified "qemu" CPU model under TCG

Before we were able to bump up the qemu CPU model to a z13, we included
some experimental features during development in the "max" model only.
Nowadays, the "max" model corresponds exactly to the "qemu" CPU model
of the latest QEMU machine under TCG.

Let's remove all the special casing, effectively making both models
match completely from now on, and clean up.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220428094708.84835-4-david@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>