Fix HoTT telemetry to use a 3ms delay between each transmitted byte.

This has fixed HoTT telemety data on my GR-24, previously it was a bit
intermittent.

This commit also marks a test-point, HoTT works on UART2.

Reference:
https://code.google.com/p/hott-for-ardupilot/source/browse/APM/Hott.pde#510