change usages of const_param_default query to bound_const_param_default

src/librustdoc/clean/mod.rs

@@ -506,7 +506,9 @@ fn clean_generic_param_def<'tcx>(
                     Some(def.def_id),
                 )),
                 default: match has_default {
-                    true => Some(Box::new(cx.tcx.const_param_default(def.def_id).to_string())),
+                    true => Some(Box::new(
+                        cx.tcx.bound_const_param_default(def.def_id).subst_identity().to_string(),
+                    )),
                     false => None,
                 },
             },