Automatic LPS mode detection should not transmit in TDoA mode

[krichardsson]

When the Crazyflie with an LPS deck is started, it tries to figure out if it should run in TDoA or TWR mode. If the LPS system is in TDoA mode it is important that the CF does not transmit any UWB messages as this might confuse other Crazyflies or anchors. The expected start up sequence should be:

1. Try to detect if the system is in TDoA mode (which does not require any transmissions)
2. If TDoA is detected, stay in TDoA - done
3. Transmit a TWR message and check for responses
4. If response is received, stay in TWR mode - done
5. Repeat

Current behaviour seems to be the other way around as the TX LED of the LPS deck is flashing, even if the system is in TDoA mode