Skip checking display windowing mode if TDA is null

This CL fixes the crash issue in CTS which uses non-trusted virtual
displays.
Such a display is not “organized” by the DisplayOrganizer so
DisplayAreaInfo can be null.

Bug: 380441549
Flag: EXEMPT bug fix
Test: com.android.test.input.UinputRecordingIntegrationTests
Change-Id: I91eed17c6fd23cad9dd1aaeab5bd541503338b34