Fix shade not closing on clear all when locked

Although we're calling NSSL#clearNotifications with closeShade=true, the
actual runnable for closing the shade leads to
ShadeControllerImpl#animateCollapseShade. This has an early return if
we're not actually on the shade, but it only checks StatusBarState.SHADE
and doesn't consider the case where we're on the lockscreen.

Fix: 328448347
Test: have lots of notifications, lock device, press clear all
Flag: NONE
Change-Id: I7e9351ae515c0577204d7c95662aeacdabcb5ca8