[FIX] sap.m.MultiComboBox: Editable state was not rendered initially

- Re-applying the state onBeforeRendering solves that problem.

Change-Id: I924b28d046b22016ad601245c2ed0016be9cec9e
BCP: 1472010633
Merge "[FIX] sap.m.MultiComboBox: Editable state was not rendered initially"