altos/telefire: Radio status (no data, weak data, good data) on LEDs

Instead of blinking RX/TX, report the radio status on the telefire
nodes, just like telelco does. This makes the LEDs on telefire
*exactly the same* as the LEDs on telelco, which seems like a good idea.

Signed-off-by: Keith Packard <keithp@keithp.com>