Incomplete mDNS device advertisements

```json
{
  "name": "elrs_txbp_1CDBD4CE2514",
  "dns": "elrs_txbp.local",
  "ip": "192.168.88.113",
  "deviceName": "",
  "target": "ESP32C3_TX_BACKPACK",
  "type": "txbp",
  "vendor": "elrs",
  "version": "1.5.4 (c3da79)"
}
```

`deviceName` is empty, which stops the configurator to matching with the exact device