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/LayerInfo.h b/services/surfaceflinger/Scheduler/LayerInfo.h
index 18ed95e..690abda 100644
--- a/services/surfaceflinger/Scheduler/LayerInfo.h
+++ b/services/surfaceflinger/Scheduler/LayerInfo.h
@@ -82,6 +82,8 @@
 
         NoVote, // Layer doesn't have any requirements for the refresh rate and
                 // should not be considered when the display refresh rate is determined.
+
+        ftl_last = NoVote
     };
 
     // Encapsulates the frame rate and compatibility of the layer. This information will be used