s390x/tcg: Use guest_addr_valid() instead of h2g_valid() in probe_write_access()

s390x/tcg: Use guest_addr_valid() instead of h2g_valid() in probe_write_access()

If I'm not completely wrong, we are dealing with guest addresses here
and not with host addresses. Use the right check.

Fixes: c5a7392cfb96 ("s390x/tcg: Provide probe_write_access helper")
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20190826075112.25637-2-david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>