The CRTC_STEREO_DOUBLE_ONLY define was introduced in commit:

  commit ecb7e16b
  Author: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
  Date:   Mon Dec 1 15:40:09 2014 -0800

      drm: add helper to get crtc timings (v5)

but if we want the stereo h/v adjustments, we need to set the
CRTC_STEREO_DOUBLE flag. Otherwise, we'll get the wrong h/v for frame packing
stereo 3d modes.

Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>