Major fixes to Oscillator code.

* Fix LO step to be 1kHz after divide-by-4.
* Add fine-tune function to quickly step LO after initialization.
* Turn off LO when char device is closed.
* Tool to observe performance of LO across frequencies.
* Only write registers that have changed for ADF4351.
* Locked ioctl for ADF4351 and CMX991.
* Move more of library to mmap interface.
* Test to make sure ADF4351 responds to SPI commands.
* Test to make sure CMX991 responds to SPI commands.
* Turn on Power Management in the Kernel - need wakeup-able
  interrupts to make this useful (GPIO & RTC.)