[UI] do not warn timezone mismatch if router is on UTC

It's a common practice to run servers / network devices in UTC so they don't need to deal with DST / timezone conversions. Is there a way to get rid of the exclamation mark when router uses UTC as timezone (when browser is in a different timezone)?

It is just the browser complaining. So close the browser and forget about it.

The reason for this is that the parental control module need to run based on the correct timezone settings.