DONE:
    - functionality similar to logic testbench

TODO:
	- checkpatch.pl cleanups.
	- keep state of DMA engines.
	- keep data structure that keeps state of each transfer.
	- interrupt handler should iterate over outstanding descriptor tables.
	- complete userspace cdev to read/write using the DMA engines.
	- split off the DMA support functions in a module, re-usable by custom
	  drivers.

Please coordinate work with, and send patches to
Leon Woestenberg <leon@sidebranch.com>