drm/i915: Try to make bigjoiner work in atomic check

 When the clock is higher than the dotclock, try with 2 pipes enabled.
 If we can enable 2, then we will go into big joiner mode, and steal
 the adjacent crtc.

 This only links the crtc's in software, no hardware or plane
 programming is done yet. Blobs are also copied from the master's
 crtc_state, so it doesn't depend at commit time on the other
 crtc_state.

v6:
* Enable dSC for any mode->hdisplay > 5120
v5:
* Remove intel_dp_max_dotclock (Manasi)
v4:
* Fixes in intel_crtc_compute_config (Ville)
v3:
* Manual Rebase (Manasi)
 Changes since v1:
 - Rename pipe timings to transcoder timings, as they are now different.
  Changes since v2:
 - Rework bigjoiner checks; always disable slave when recalculating
   master. No need to have a separate bigjoiner pass any more.
 - Use pipe_mode instead of transcoder_mode, to clean up the code.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
[vsyrjala:
* hskew isn't a thing
* Do the dsc compute if bigjoiner is enabled, not the other way around]
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201117194718.11462-4-manasi.d.navare@intel.com