fix(radio): Lua insertMix function not working

[philmoz]

Fixes #4128

Needs to be applied to 2.9 as well as main. Broken in PR #4008/#3999

[pfeerick]

LGTM... Lua is now correctly inserting and manual insert is still working (2.9 does not need the mixes.cpp change).

local function init()
  model.insertMix(8,0, {name="Gain9M", switch=19, source=118, weight=80, multiplex=0, speedDown=0, speedUp=0, delayDown=0, delayUp=0, carryTrim=true, offset=0, flightModes=0, curveValue=0, curveType=0})
  model.insertMix(8,1, {name="Gain9+", switch=20, source=110, weight=30, multiplex=0, speedDown=0, speedUp=0, delayDown=0, delayUp=0, carryTrim=true, offset=0, flightModes=0, curveValue=0, curveType=0})
  model.insertMix(8,2, {name="Gain9", switch=21, source=110, weight=25, multiplex=0, speedDown=0, speedUp=0, delayDown=0, delayUp=0, carryTrim=true, offset=0, flightModes=0, curveValue=0, curveType=0})
end

local function run(event, touchState)
  return 1
end

return { run=run, init=init }