Removed class HdmiCec

Most of the constants in HdmiCec are internal use only. Moved them
to service, and dispersed the rest to other relevant classes.

Also moved HdmiCecMessage class to service as it doesn't need to be
open ouside the service.

Change-Id: I7b2ce3bf465330aa4d7fcd05f9aefa1e6c8b056a