telit: try SPI bus communication
Set cpuidle as default trigger for cpu-led
telit: add config option to  switch on during startup
uart-stellaris: bux fix commit

- Fix hang if receves quite big chunk of data;
- Fix performance issue (change work_queue to tasklet);
- Fix DOS (do not react with interrupt on every received byte);
- Worning fixes
atlas: tune uarts dma buffer size