Make sure we update the visibility of fields based on all day event or not.

Was just doing this in the case of the user not being able to edit,
but needs to do it when the user can edit as well.

Fixes b/6408966 EditEventActivity shows time zone when opening an all-day event

Change-Id: Ib9cbcdc4b9c3764aa7f10a9ef2f1304da94abb43