HDMI stereo support v4

Damien Lespiau
2013-09-16T17:48:43Z

Next installment of the HDMI stereo 3D series, following:
http://lists.freedesktop.org/archives/dri-devel/2013-September/044885.html

Quite a few changes here, and it's starting to "feel right":
- We now expose each stereo layout as a separate mode, distinct from the 2D
mode, instead of piggybacking on the 2D mode flags.
- 2 bugs fixed:
- We also expose 3D layouts of modes with alternate clocks
- The VIC field in the AVI infoframe is now correctly set to the
corresponding 2D mode
- We forbid the use of frambuffers with 2 buffers to not set any precedent
before we can explore the interactions of such framebuffers with the rest
of the DRM API
- Rename SET_CAP to SET_CLIENT_CAP