Add an example program (in Python) for the AMD Am79c900 (ILACC)
ethernet controller. The ethernet controller is emulated by VMware
Fusion (for example) and is a good device to demonstrate how to use
the bus space and busdma functions due to its simple programming.

The program sets up the DMA structures, sends a DHCP discover packet,
waits 2 seconds, and iterates over the receive ring for an offer.