SF: Remove DisplayDevice visible layer members

There are no longer any consumers of it, so the data and related functions
are removed, and the bit of code that was still setting it is removed.

Test: atest libsurfaceflinger_unittest libcompositionengine_test
Bug: 121291683
Change-Id: If09254dc44645b816d88b89cda64284822dd43ed
4 files changed