Revert needless modification of published UNO API

This reverts the part of 4452ac23224cc6fc9c575f1b128dd71f79e12d88 "Fix hungarian
prefix for calendars" that needlessly changed a method parameter name in
published UNO API, which is, strictly speaking, incompatible.

Change-Id: Icd1ee34d200ebab01010d5dd35a1b19c47bfc05a