Camera: Query default display size from display manager

The current Android API will trigger strict mode
violations in case a context not bound to any
particular display tries to connect to the window
manager service.
To avoid such violations query the default display size
directly from the display manager.

Bug: 157167435
Test: Camera CTS
Change-Id: Icad19ec0227b4945da9e6fcacaec916c5799877f