Layer: Don't need atomic for transaction flags

Following queued transaction changes we don't need an atomic here
since setPosition etc all execute on the main thread.

Test: Existing tests pass. simpleperf
Bug: 186200583
Change-Id: I965d3883d30ce1eb3c452742535281f3e2719424
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 5873103..5669049 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -960,7 +960,7 @@
 
     // these are protected by an external lock (mStateLock)
     State mCurrentState;
-    std::atomic<uint32_t> mTransactionFlags{0};
+    uint32_t mTransactionFlags{0};
 
     // Timestamp history for UIAutomation. Thread safe.
     FrameTracker mFrameTracker;