QuickSettings : Register/unregister cast tile one time

Don't do these operations every time the parent is visible/invisible,
it causes jank.

Repro:

Turn on wifi on a network w/ chromecast
Swipe down quick settings panel really fast

Change-Id: I3dfcd3610abe96e1bfdab06ef3b876ccf5140ceb
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0