PX4Magnetometer implement MAGIOCGSCALE (copy out scale)
PX4Magnetometer implement MAGIOCGSCALE (copy out scale)

- fixes #12193
dagar/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,acfloria/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,acfloria/Firmware,mje-nz/PX4-Firmware,dagar/Firmware,acfloria/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,dagar/Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware,mje-nz/PX4-Firmware,krbeverx/Firmware,krbeverx/Firmware,PX4/Firmware,krbeverx/Firmware,krbeverx/Firmware,dagar/Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware,dagar/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,dagar/Firmware,acfloria/Firmware,PX4/Firmware,PX4/Firmware,mje-nz/PX4-Firmware