Fix MSP V1 format - missing function byte in response

[JimB40]

Tested on INAV 8.0.0

Current Behavior

Current MSP V1 has bug and doesn't adhere to MSP V1 spec.
https://github.com/iNavFlight/inav/wiki/MSP-V2#legacy-and-compatibility

function byte is not send after payload size

This leads to numerous errors as we doesn't know if response coming is for actual request sent.
That leads to wrong data parsing.

Expected behavior

function byte should be sent after payload size and before actual payload bytes

[DzikuVx]

What exactly are we looking at? According to a MSPV1 frame outgoing from FC should begin with $M> that converts to HEX 24 4D 3E and I don't see this sequence anywhere. Is this even MSP frame?

[JimB40]

MSP V1 over telemetry. CRSF frame where '$M>' are stripped.
So first 3 bytes in this dump are CRSF specyfic.
4th is MSP packet length.
5th should be MSP function (missing)
Then actual MSP payload goes.

[DzikuVx]

@JimB40 here is potential fix #10671 could you please test it?