drm/i915: Don't set the 8to6 dither flag when not scaling

Apparently we really only need this when the pfit is enabled, at least
I couldn't dicern any difference here. Furthermore the hacks we have
to reconstruct this bit is a bit glaring, and probably only works
because we can't move the lvds port to any other pipe than pipe B on
gen2/3.

So let's just rip this out.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77137 (the LVDS
WARNING log, not the main "VGA can't be turned on" issue).
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_lvds.c

@@ -111,13 +111,6 @@ static void intel_lvds_get_config(struct intel_encoder *encoder,
 
 	pipe_config->adjusted_mode.flags |= flags;
 
-	/* gen2/3 store dither state in pfit control, needs to match */
-	if (INTEL_INFO(dev)->gen < 4) {
-		tmp = I915_READ(PFIT_CONTROL);
-
-		pipe_config->gmch_pfit.control |= tmp & PANEL_8TO6_DITHER_ENABLE;
-	}
-
 	dotclock = pipe_config->port_clock;
 
 	if (HAS_PCH_SPLIT(dev_priv->dev))

drivers/gpu/drm/i915/intel_panel.c

@@ -308,16 +308,16 @@ void intel_gmch_panel_fitting(struct intel_crtc *intel_crtc,
 		pfit_control |= ((intel_crtc->pipe << PFIT_PIPE_SHIFT) |
 				 PFIT_FILTER_FUZZY);
 
+	/* Make sure pre-965 set dither correctly for 18bpp panels. */
+	if (INTEL_INFO(dev)->gen < 4 && pipe_config->pipe_bpp == 18)
+		pfit_control |= PANEL_8TO6_DITHER_ENABLE;
+
 out:
 	if ((pfit_control & PFIT_ENABLE) == 0) {
 		pfit_control = 0;
 		pfit_pgm_ratios = 0;
 	}
 
-	/* Make sure pre-965 set dither correctly for 18bpp panels. */
-	if (INTEL_INFO(dev)->gen < 4 && pipe_config->pipe_bpp == 18)
-		pfit_control |= PANEL_8TO6_DITHER_ENABLE;
-
 	pipe_config->gmch_pfit.control = pfit_control;
 	pipe_config->gmch_pfit.pgm_ratios = pfit_pgm_ratios;
 	pipe_config->gmch_pfit.lvds_border_bits = border;