ntpclient: update config with functional ntp servers
It seems that XX.openwrt.pool.ntp.org servers are not working properly. Maybe we should replaced them with servers for lede (0.lede.pool.ntp.org ...)
Related forum thread: https://forum.turris.cz/t/prihlaseni-na-gitlab-a-zmeny-ntp-serveru/6257
Note: For some reason openwrt package is still using openwrt.pool.ntp.org servers. https://github.com/openwrt/packages/blob/master/net/ntpclient/files/ntpclient.config