[BUG] - Brightness Sensor not changing.
**Describe the bug**
Installed this with the CFW on a new Wyzecam V2.  The motion sensor and other items work, but brightness seems stuck at 40.  I can sit in a dark room and it doesn't change.

**Expected behavior**
The expected behavior is to change with the brightness in the room. If the room is dark the value should approach 0.  As it gets brighter it should approach 100.

**Config**
`{
            "platform": "Dafang",
            "mqtt": {
                "hostBroker": false,
                "port": 1883,
                "host": "192.168.1.90",
                "debug": true
            },
            "cameras": [
                {
                    "cameraName": "Backyard wyzev2-0001",
                    "cameraRTSPStreamUrl": "rtsp://192.168.1.226:8554/unicast",
                    "mqttTopic": "BACKYARD/wyzev2-0001/#",
                    "disableStream": false,
                    "folder": "/homebridge/recordings/",
                    "segmentLength": 60,
                    "maxDirSize": 4096,
                    "checkStorageSizeInterval": 300,
                    "recordingDirectoryPathFormat": "MMM-D-YY",
                    "recordingFilenameFormat": "M_D_YYYY_ h_mm_ss_a",
                    "accessories": [
                        {
                            "name": "Backyard Motion Sensor",
                            "type": "richMotionSensor",
                            "threshold": 3000000
                        },
                        {
                            "name": "Backyard Auto Motion Tracking Switch",
                            "type": "autoMotionTrackingSwitch"
                        },
                        {
                            "name": "Backyard Night Vision Sensor",
                            "type": "nightVisionSensor",
                            "threshold": 0
                        },
                        {
                            "name": "Backyard Night Vision Switch",
                            "type": "nightVisionSwitch"
                        },
                        {
                            "name": "Backyard Auto Night Vision Switch",
                            "type": "autoNightVisionSwitch"
                        },
                        {
                            "name": "Record Video",
                            "type": "recordVideo"
                        },
                        {
                            "name": "Record Audio",
                            "type": "recordAudio"
                        },
                        {
                            "name": "Capture Image",
                            "type": "captureImage"
                        },
                        {
                            "name": "RPi Storage Sensor",
                            "type": "storageSensor"
                        },
                        {
                            "name": "Clear Storage Switch",
                            "type": "clearStorage"
                        },
                        {
                            "name": "Reset Streaming",
                            "type": "resetFFMPEG"
                        },
                        {
                            "name": "Motion Detection Switch",
                            "type": "motionDetection"
                        },
                        {
                            "name": "RTSPSwitch",
                            "type": "rtspSwitch"
                        },
                        {
                            "name": "MJPEG Switch",
                            "type": "mjpegSwitch"
                        },
                        {
                            "name": "Recalibrate Switch",
                            "type": "recalibrateSwitch"
                        },
                        {
                            "name": "Restart Switch",
                            "type": "restartSwitch"
                        },
                        {
                            "name": "ReMount Switch",
                            "type": "remountSwitch"
                        },
                        {
                            "name": "Camera Brightness",
                            "type": "brightness"
                        }
                    ],
                    "videoConfig": {
                        "source": "-rtsp_transport tcp -i rtsp://192.168.1.226:8554/unicast",
                        "stillImageSource": "-rtsp_transport http -i rtsp://192.168.1.226:8554/unicast -vframes 1 -r 1",
                        "maxStreams": 5,
                        "maxWidth": 1280,
                        "maxHeight": 720,
                        "maxFPS": 30,
                        "vcodec": "h264",
                        "debug": true
                    }
                }
            ]
        }`
**Logs**
Share the logs with debug as true in config.json

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Desktop (please complete the following information):**
 - OS: Synology Docker Container
 - Node Version: 10.14.2

**Additional context**
Add any other context about the problem here.
