Remove a non-obvious fall through in a switch statement.

This CL does not modify the result of calling onInterceptHoverEvent()
assuming isEventOverFolder() has no side effects. The only change is
that isEventOverFolder will now be called once rather than twice when
action == MotionEvent.ACTION_HOVER_ENTER and isOverFolder == true.

Change-Id: Icc28ab880cf5094e49f51d72035891e924cb2031