drm/i915/mst: Fix .mode_valid_ctx() return values

.mode_valid_ctx() returns an errno, not the mode status. Fix
the code to do the right thing.

Cc: stable@vger.kernel.org
Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Fixes: d51f25e ("drm/i915: Add DSC support to MST path")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231127145028.4899-2-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit c179903)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Author: vsyrjala

drivers/gpu/drm/i915/display/intel_dp_mst.c

@@ -1031,11 +1031,15 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
 	 * Big joiner configuration needs DSC for TGL which is not true for
 	 * XE_LPD where uncompressed joiner is supported.
 	 */
-	if (DISPLAY_VER(dev_priv) < 13 && bigjoiner && !dsc)
-		return MODE_CLOCK_HIGH;
+	if (DISPLAY_VER(dev_priv) < 13 && bigjoiner && !dsc) {
+		*status = MODE_CLOCK_HIGH;
+		return 0;
+	}
 
-	if (mode_rate > max_rate && !dsc)
-		return MODE_CLOCK_HIGH;
+	if (mode_rate > max_rate && !dsc) {
+		*status = MODE_CLOCK_HIGH;
+		return 0;
+	}
 
 	*status = intel_mode_valid_max_plane_size(dev_priv, mode, false);
 	return 0;