drm/connector: update edid_blob_ptr documentation

Accessing the EDID via edid_blob_ptr causes chicken-and-egg
problems. Keep edid_blob_ptr as the userspace interface that should be
accessed via dedicated functions.
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b6aa1ea30ae85ef9e9814315d3437e82f0ba6754.1715353572.git.jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>

include/drm/drm_connector.h

@@ -1636,8 +1636,12 @@ struct drm_connector {
 
 	/**
 	 * @edid_blob_ptr: DRM property containing EDID if present. Protected by
-	 * &drm_mode_config.mutex. This should be updated only by calling
+	 * &drm_mode_config.mutex.
+	 *
+	 * This must be updated only by calling drm_edid_connector_update() or
 	 * drm_connector_update_edid_property().
+	 *
+	 * This must not be used by drivers directly.
 	 */
 	struct drm_property_blob *edid_blob_ptr;