Transmit transport end-to-end.

* Start using universal debug statements.
* Complete & test fsync; tx transport now getting all samples across.
* Fix race condition on DMA getting enough samples to peripheral before a
  call to TXEN.
* Fix unaligned access on the user source buffer.
* Add CMX991 test for response to a change in the register file.
* Fix bug in computing the CMX991's register file from choosing
  the RF synthesizer's frequency.
* Mess with the DSP code.  The limiting factor seems to be memory
  throughput right now.
* Turn on gcc debug.