drm/i915: Disallow interlaced modes on g4x DP outputs

Looks like interlaced DP output doesn't work on g4x either. Not all
that surprising considering we already established that interlaced
DP output is busted on VLV/CHV.

Cc: stable@vger.kernel.org
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180613160553.11664-1-ville.syrjala@linux.intel.com
(cherry picked from commit 929168c5)
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_dp.c

@@ -1868,7 +1868,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
 		return false;
 
-	if ((IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) &&
+	if (HAS_GMCH_DISPLAY(dev_priv) &&
 	    adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE)
 		return false;
 
@@ -6343,7 +6343,7 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 	drm_connector_init(dev, connector, &intel_dp_connector_funcs, type);
 	drm_connector_helper_add(connector, &intel_dp_connector_helper_funcs);
 
-	if (!IS_VALLEYVIEW(dev_priv) && !IS_CHERRYVIEW(dev_priv))
+	if (!HAS_GMCH_DISPLAY(dev_priv))
 		connector->interlace_allowed = true;
 	connector->doublescan_allowed = 0;