Correct display dimensions considered.

This changelist makes sure the full screen size is considered
when accounting for the dream overlay.  Previously, insets would
be subtracted from the overall dimensions.

Test: atest DreamOverlayTouchMonitorTest#testReportedDisplayBounds
Fixes: 267565290
Change-Id: I48c072491efc62c49385ae5f4684d99585a05895
Merged-In: I48c072491efc62c49385ae5f4684d99585a05895