hw/mem/cxl_type3: Fix potential divide by zero reported by coverity

hw/mem/cxl_type3: Fix potential divide by zero reported by coverity

Fixes Coverity ID 1522368.

Currently error_fatal is set if interleave_ways_dec() is going to return 0
but we should handle that zero return explicitly.

Reported-by: Stefan Hajnoczi <stefanha@gmail.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20240126120132.24248-10-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>