SystemUI: NavbarEditor: Fix saveKeys logic

In landscape, the keys are saved backwards in the for-loop, but it would crash out due from
an IndexOutOfBounds error since it's subtracting i from the array length while i = 0.

Change-Id: I405c5d962d8c575cfee57b09a7e55a8a6efc2d24
Merge "SystemUI: NavbarEditor: Fix saveKeys logic" into du44