SPINEL_PROP_MAC_SCAN_STATE value

MAC Scan State Format: `C` Possible values are from enumeration `spinel_scan_state_t`. SCAN_STATE_IDLE SCAN_STATE_BEACON SCAN_STATE_ENERGY SCAN_STATE_DISCOVER Set to `SCAN_STATE_BEACON` to start an active scan. Beacons will be emitted from `PROP_MAC_SCAN_BEACON`. Set to `SCAN_STATE_ENERGY` to start an energy scan. Channel energy result will be reported by emissions of `PROP_MAC_ENERGY_SCAN_RESULT` (per channel). Set to `SCAN_STATE_DISCOVER` to start a Thread MLE discovery scan operation. Discovery scan result will be emitted from `PROP_MAC_SCAN_BEACON`. Value switches to `SCAN_STATE_IDLE` when scan is complete.