CX820 support for h264 main stream and HDR always on

[user_963911108411591_963911108411591]

For CX820 add support for h264 main stream and HDR force On support.

These feature are already present in rest of CX and other series while missing from CX820, this make it unnecessary complex/degraded picture quality to integrate with home automation like Google, HomeKit etc. as in general all platform require h264