Revert "SurfaceFlinger: protect state members in Layer"

State update transactions must be atomic. The fine-grained lock on each
Layer implied otherwise. Revert the fine grained lock as being
unhelpful.

Unfortunately there does not seem to be a way to use Clang thread
annotations to specify the desired locking behavior.

Note that the parent CL addresses the locking problem that led to the
bug.

This reverts commit 83729883.

Bug: 119481871
Test: SurfaceFlinger unit tests
Test: go/wm-smoke
Change-Id: I361741f8d10102aeb57f164c847c6063ff93dd14