DIMM CAD structures could probably be simplified

[rmustacc]

Right now the RDIMM and LRDIMM cad structures end up being very repetitive because we need to define several different instances of this, often with three version per speed (1 DPC, 2 DPC 1 pop, 2DPC 2 pop). We could probably come up with a simpler syntax that will expand this and do the right thing and allow someone to specify which of these versions they care about.