Fix navbar clipping

Instead of clipping on the navbar, as the QS background takes the whole
screen, just have a padding the size of the navbar. That way, when the
QS container is scrolled completely to the bottom, no view is obstructed
by the nav bar.

Test: manual
Fixes: 187444362
Change-Id: If22f46a27d48066571ba5c2193c9f6e2e0c3fe24