Add support for CPM device tree configuration to 8560 ADS

* Adds code to modify CPM frequencies
* Cleans up the config file to #define TSEC and (for now) #undef FCC
* Adds the MII command for all 8560 ADS configurations
* Updates config file to provide convenience commands for booting
  with a device tree

Signed-off-by: Vitaly Bordug <vbordug@ru.mvista.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>