Use physical density for external displays

The CL has LocalDisplayAdapter use physical density from surface
flinger.  Previously LocalDisplayAdapter always uses fake density for
external displays. The fake density is no longer needed because surface
flinger fills density always now.

Bug: 144066777
Test: LocalDisplayAdapterTest
Change-Id: I105de4f6ded17c6882d98e60e8c7d7c027299f56
2 files changed