s390x/tcg: ASI/ASGI/ALSI/ALSGI are atomic with Interlocked-acccess facility 1

The semantics of ASI/ASGI/ALSI/ALSGI changed. Let's implement them just
like LOAD AND ADD, so they are atomic. Emulate old behavior.

This fixes random crashes when booting a Linux kernel compiled for
z196+ with SMP + MTTCG.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20171208160207.26494-7-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
