fix regression from 0d95625c, re #957

lib/phplib/Seminar_Perm.class.php

@@ -219,12 +219,8 @@ class Seminar_Perm
     {
         $pageperm = $this->permissions[$perm] ?? 0;
         $userperm = $this->permissions[$this->get_studip_perm($range_id, $user_id)] ?? 0;
-        if ($userperm) {
-            return $pageperm <= $userperm;
-        } else {
-            //The user has no permissions at all.
-            return false;
-        }
+
+        return $pageperm <= $userperm;
     }
 
     /**