Fix bug with Overview tile cropping in flexible split

Fixes a small typo that was resulting in one Overview case (swiping to Overview in portrait mode in 90:10 split) being drawn with the wrong ratio.

Fixes: 391899871
Flag: com.android.wm.shell.enable_flexible_two_app_split
Test: Repro case has the correct behavior now.
Change-Id: I4874e14f9d5431097196eb61ad8d1cfd468874df