Fix QS lock screen animation

Now that we have a footer, heights and clippings need to be adjusted
to be more accurate.
 - Clip QS within its layout box regardless of its y translation
 - Calculate height diffs correctly

Test: visual
Change-Id: Ic46996e342cd1000215aa9256da920a7856bb5a4
Fixes: 62489284
(cherry picked from commit bdefffd1e806f8b7ffd5fdbe8159bee2c9d5bbb0)
2 files changed