hwc2: set layer visible region

Test: Add "TARGET_USES_HWC2 := true" to BoardConfig.mk.
      Recompile.
      Run testcases: https://android-review.googlesource.com/#/q/project:
            platform/frameworks/native+branch:master+topic:test-hwc2

Change-Id: I127ddcc97ebc1fc0c01fac060d7e17f33e182f3c
6 files changed