drm/i915: Move scanline_offset and timestamping constant setup to intel_modeset_readout_hw_state()

intel_modeset_readout_hw_state() seems like the more appropriate place
for populating the scanline_offset and timestamping constants than
intel_sanitize_crtc() since they are basically part of the state we
read out.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -14907,8 +14907,6 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc)
 	if (crtc->active) {
 		struct intel_plane *plane;
 
-		drm_calc_timestamping_constants(&crtc->base, &crtc->base.hwmode);
-		update_scanline_offset(crtc);
 		drm_crtc_vblank_on(&crtc->base);
 
 		/* Disable everything but the primary plane */
@@ -15204,6 +15202,9 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
 			 * recalculation.
 			 */
 			crtc->base.state->mode.private_flags = I915_MODE_FLAG_INHERITED;
+
+			drm_calc_timestamping_constants(&crtc->base, &crtc->base.hwmode);
+			update_scanline_offset(crtc);
 		}
 	}
 }