DeskClock: Fix search menuitem does not work.

SearchView cannot be expanded when it is in the menu outflow list, so
cannot function normally when user click search menuitem.

Set the search menuitem showAsAction to always, which will make sure
SearchView can be normally expanded.

Change-Id: I57a6603f0f4805be68302ec12ea08f522fabac67
CRs-Fixed: 1079495