Update home to overview depth interpolator to match other motion

Overview comes in and workspace goes out at overshoot(1.2), so
the wallpaper depth/blur should match that speed.

Test: go to overview from home in 3 button or 0 button mode,
ensure wallpaper scales down at the same rate as other elements

Bug: 154637581
Change-Id: I03254fa3fdf19f468852bed8aab7ba21203c429a