kick out of hci_event_handler

waits 10 seconds before kicking out of the CC3k death loop
This will break when the timer wraps.

Use something like
```
unsigned cc3000_start_time = tm_timestamp();
...
if (tm_timestamp() - cc3000_start_time > CC3000_MAX_WAIT) { ...
```
such that the subtraction will unwrap the integer.