Only call onDisplayAreaInfoChanged if config actually changed

onConfigurationChanged is called pretty frequently if anything in the
hierarchy changed. Avoid sending duplicate callbacks to the client if
the configuration didn't actually change.

Test: Rotate, only unique configurations in onConfigurationChanged
Test: DisplayAreaOrganizerTest
Fixes: 156677444
Change-Id: Icf4dc8a0a5f7bdcfac87721c6ff656f2fe711a90