[FIX] sap.m.ActionSelect: disabled items are incorrectly displayed

- fix display of disabled items in ActionSelect according
  to the visual specification

Change-Id: I2a12b5b01950c18bab62777dd2ad2a4ab86145ae
CR-Id: 012006153200014998912014
Merge "[FIX] sap.m.ActionSelect: disabled items are incorrectly displayed" into rel-1.26