Provide standard ethernet interface to kernel for raw ethernet channel on CIFX-RE cards

Currently it is not possible to attach the raw ethernet channel that is available on most real-time ethernet firmwares to the linux kernel. This would allow to perform standard socket and network operations from any application. This can be achieved by using a tap device provided by kernel module tun.ko

This feature is comparable to the NDIS driver which is available for Windows.

NOTE: The firmware will offer an additional MAC address to the host, which requires an IP address, that must be different from the one used by the fieldbus system on the cifX device