drm/i915: Complete crtc hw/uapi split, v6.

drm/i915: Complete crtc hw/uapi split, v6.

Now that we separated everything into uapi and hw, it's
time to make the split definitive. Remove the union and
make a copy of the hw state on modeset and fastset.

Color blobs are copied in crtc atomic_check(), right
before color management is checked.

Changes since v1:
- Copy all blobs immediately after drm_atomic_helper_check_modeset().
- Clear crtc_state->hw on disable, instead of using clear_intel_crtc_state().
Changes since v2:
- Use intel_crtc_free_hw_state + clear in intel_crtc_disable_noatomic().
- Make a intel_crtc_prepare_state() function that clears the crtc_state
  and copies hw members.
- Remove setting uapi.adjusted_mode, we now have a direct call to
  drm_calc_timestamping_constants().
Changes since v3:
- Rename prefix copy_hw_to_uapi_state() with intel_crtc.
- Copy color blobs to uapi as well.
- Add a intel_crtc_copy_uapi_to_hw_state_nomodeset() function for clarity.
Changes since v4:
- Copy hw.adjusted_mode back to uapi.adjusted_mode, to shut up
  the call to drm_calc_timestamping_constants() in
  drm_atomic_helper_update_legacy_modeset_state().
- Use drm_property_replace_blob (Ville).
Changes since v5:
- Use hw->mode in intel_modeset_readout_hw_state(). (Ville)
- Copy to uapi.mode using drm_atomic_set_mode_for_crtc(). (Ville)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191031112610.27608-6-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>