Avoid playing taskbar haptic when swiping up from home

Only play the haptic if the stashed value actually changed. In the
case of home-to-overview, taskbar is unstashed already.

Fixes: 314311118
Flag: none
Test: Manual, feel for haptics during home-to-overview
Change-Id: I36f70740d35bd98feafbb3980f861db16705b1da