s390x/tcg: Implement VECTOR MULTIPLY SUM LOGICAL

Fortunately, we only need the Doubleword implementation.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210608092337.12221-13-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>