Allow temperature updates when WEATHER is OFF

[MichelMoriniaux]

My JTW controller does not have a BME280 chip so WEATHER is set to OFF as such firstScanDone never flips and the code that averages out temperature updates is never run. this means that a :SX9A command does not update the temperature.

This allows for offline updates of weather parameters ( diffraction based tracking ) by an external process. for eg. read a weather station and update temperature, humidity and pressure by using the command channel with SX9 commands