CRSF battery frame is big-endian: voltage(u16 BE 0.1V),
current(u16 BE 0.1A), capacity(u24 BE mAh), remaining(u8 %).
Previous code read little-endian with wrong byte count (7 vs 8)
and wrong scaling (/1000 vs /10), producing 9.98V for a 1S battery.
cel_crsf_telemetry_parse() decodes link stats, battery, heartbeat,
and airspeed frames. Updated cel_telem_battery and cel_telem_airspeed
structs to use uint16_t values matching CRSF protocol format.
portersky