No longer require server priv for /at_sync_ndb

The check for server priv was hidden where no one would have expected
it.

advtrains/nodedb.lua

@@ -293,7 +293,7 @@ minetest.register_chatcommand("at_sync_ndb",
         privs = {train_operator=true}, 
         func = function(name, param)
 			return advtrains.pcall(function()
-				if not minetest.check_player_privs(name, {server=true}) and os.time() < ptime+30 then
+				if os.time() < ptime+30 then
 					return false, "Please wait at least 30s from the previous execution of /at_restore_ndb!"
 				end
 				local text = ndb.restore_all()