How it works:
1. Current Meter Source on FC is set to MSP/OSD Slave by user.
2. On reboot FC sends MSP_ANALOG to OSD Slave.
3. OSD Slave listens for incoming MSP as usual.
4. OSD responds to MSP as usual.
6. The FC recevies the data from the OSD Slave and updates the MSP
Current Meter.
the flight controller code.
Likely the dependencies can be further improved. This is a
minimal-impact solution while there are a lot of other Betaflight PR's
still pending.
