CDL doesn't support multiple physical device but just assert

[christophe-lunarg]

void Device::MemoryBindEvent(const DeviceAddressRecord& rec, bool multi_device) {

    // Because log callbacks are instance level, we'll get a stream of events
    // for all devices in the system. Th.secondis code assumes there's only one.
    // If there are multiple devices, each will need to filter events by looking
    // up the vulkan handle. This will be slow.
    assert(!multi_device);

instead we should output a warning...

[jeremyg-lunarg]

This should only be hit if there's multiple VkDevices active at the same time. That's much less likely IMO but yes evetually we should do something better here.