Revert "SystemUI: tuner: Fix up button navigation in activity"

As the hamburger menu is also classified as a home button,
this will cause the hamburger menu to navigate backwards
when pressed.

Revert the original change for a better solution.

This reverts commit 3ea70476.

Change-Id: I1bb1efd12315ee5c63ec60932ab11f9f4e94ad71