SF: Remove manual enum stringification

Upgrade to scoped enums where applicable. Pull GameMode from TimeStats
into libgui to plumb it as an enum rather than int32_t.

Bug: 185536303
Test: libsurfaceflinger_unittest
Change-Id: I81fdd24805757ef953484055ee867684eb94fecf
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
index 8a1c206..8c38083 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
@@ -206,6 +206,7 @@
         ExplicitExact,           // Specific refresh rate that was provided by the app with
                                  // Exact compatibility
 
+        ftl_last = ExplicitExact
     };
 
     // Captures the layer requirements for a refresh rate. This will be used to determine the
@@ -285,9 +286,6 @@
     // Stores the current modeId the device operates at
     void setCurrentModeId(DisplayModeId) EXCLUDES(mLock);
 
-    // Returns a string that represents the layer vote type
-    static std::string layerVoteTypeString(LayerVoteType vote);
-
     // Returns a known frame rate that is the closest to frameRate
     Fps findClosestKnownFrameRate(Fps frameRate) const;