+3. The environment variable will be compared to the driver initialized
+ struct eth_device->enetaddr. If they differ, a warning is printed, and the
+ environment variable will be used unchanged.
+ If the environment variable is not set, it will be initialized from
+ eth_device->enetaddr, and a warning will be printed.
+ If both are invalid and CONFIG_NET_RANDOM_ETHADDR is defined, a random,
+ locally-assigned MAC is written to eth_device->enetaddr.