CEC: make it sure to send vendor commands when changing a setting.

- Remove 'oneway' from IHdmiVendorCommandListener.
- Add flush() method to HdmiCecController.
- Use IoThread for HdmiCecController.

Bug: 18495592
Change-Id: I497f7b49e94dd4402058ecc89cb5b7a3d58bf1e1
3 files changed