Smartspace in wrong position

KeyguardClockSwitch will be recreated by
NotificationPanelViewController for a variety of reasons, including
onDensityOrFontScaleChanged(). When this happens, the large/small
clock state can get out of sync with the initial state. Set the clock
state to null on creation to avoid this.

Fixes: 188390632
Test: manual, it's a race condition that can be hard to trigger
Change-Id: I49cda9afd5c708b05aba56a40d29c1cefe847de4