Sun 3 bootrom souce - replacing rarp with DHCP

The code calls RARP "revarp" and the code for this is in sys/inet.c

Another major "tweak" (much more than a tweak) will be to remove all keyboard and framebuffer code from the bootrom. I know this sounds drastic, and I'll try to make it possible to build a bootrom either with or without framebuffer support. Getting rid of the framebuffer code (and all the pixrect stuff) will open up a lot of space in the ROM, and that will probably be essential to make room for DHCP code.