drm/i915: Ask the DRM core do make stereo timings adjustements

When scanning out big stereo buffers that are actually bigger that their
natural 2D counterpart, we need to blow up the crtc timings as well.

Not that this is only done for frame packing as this is the only stereo
mode currently exposed needing this kind of ajdustements.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Acked-by: NDave Airlie <airlied@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -8468,7 +8468,7 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
 	pipe_config->pixel_multiplier = 1;
 
 	/* Fill in default crtc timings, allow encoders to overwrite them. */
-	drm_mode_set_crtcinfo(&pipe_config->adjusted_mode, 0);
+	drm_mode_set_crtcinfo(&pipe_config->adjusted_mode, CRTC_STEREO_DOUBLE);
 
 	/* Pass our mode to the connectors and the CRTC to give them a chance to
 	 * adjust it according to limitations or connector properties, and also