openthread_port: fix receive buffer overflow

components/openthread/port/esp_openthread_radio.c

@@ -422,6 +422,7 @@ void IRAM_ATTR esp_ieee802154_receive_done(uint8_t *data, esp_ieee802154_frame_i
 {
     if (s_recv_queue.used == CONFIG_IEEE802154_RX_BUFFER_SIZE) {
         ESP_EARLY_LOGE(OT_PLAT_LOG_TAG, "radio receive buffer full!");
+        return;
     }
 
     s_rssi = frame_info->rssi;