Fix race condition for clock carousel

Carousel.mMotionLayout is only ready after attachedToWindow. We can only
bind the view after attachedToWindow; otherwise, whenever the flow emits
any events before attachedToWindow and triggers calls to
Carousel.mMotionLayout, there will be a null pointer exception.

Test: Manually tested the app does not crash when emits early
Fixes: 278784117
Change-Id: Id65ed932b1526062063e453e910d16e01e1508dd