OTA legrand

Legrand release new firmware but it's impossible to update with deconz.
It stop at 0.02% .

zigbee2mqtt implement a hack here for this issue
https://github.com/Koenkk/zigbee-herdsman-converters/commit/cba37b6a7d560a0dd9420e7f06a3d74a43ce8d23

thanks