On macOS 12 and later, Apple replaced IOUSBDevice with IOUSBHostDevice
in the USB host stack. When walking the IORegistry parent chain to find
the USB device providing a serial port, the existing code only checked
IOObjectConformsTo(parent, kIOUSBDeviceClassName). On macOS 12+, this
check fails because the USB device node conforms to IOUSBHostDevice
instead.
Fix by also checking IOObjectConformsTo(parent, "IOUSBHostDevice"),
so CDCACM device discovery works on both old and new macOS.
Verified on macOS 26 (Tahoe, arm64) with a ValueCAN 4-2 (V2D805).
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