Revert "tvout: remove feature for now"

This reverts commit 72d2e6c2b0fda124feef1e50b6be236fab340eb8.

Depends on:

- https://gerrit.omnirom.org/#/c/5376/
- https://gerrit.omnirom.org/#/c/5377/

Change-Id: Ic98b008bc33c9235c2ee9aa7db60ffb122b564fe