Trebuchet: Revert animation end

Since moveToDefaultScreen is protected by mIsSwitchingState, no animation is triggered when
the home screen is double tapped. Now, cancel the animation is causing icons to disappear.

Change-Id: I3838a02d7afc4a40343c593ea743d1773bbc3cfd
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>