bbctl: do not wait full timeout for data

The KeyboardInterrupt is not delivered while waiting in the read() call,
so just loop every 100 ms instead.

Signed-off-by: Jeppe Ledet-Pedersen <jlp@satlab.org>
bbctl: remove set/get_training_ms

These are deprecated. set/get_training already sets the training
sequence length in ms.

Signed-off-by: Jeppe Ledet-Pedersen <jlp@satlab.org>