Fix potential overflow in Visualizer effect

Bug: 30229821
Change-Id: Ia07041a5a149d7d3e120aa6ea0345fb86da37c9b
(cherry picked from commit b61dd321d08b21a5629044eca7f96e2ecd348e5f)
(cherry picked from commit 7bbd5008747431d42e2f8cfbc0ddcb8465cdb4a5)
diff --git a/audio_effects/include/audio_effects/effect_visualizer.h b/audio_effects/include/audio_effects/effect_visualizer.h
index cfd99f5..fe46d7f 100644
--- a/audio_effects/include/audio_effects/effect_visualizer.h
+++ b/audio_effects/include/audio_effects/effect_visualizer.h
@@ -41,6 +41,7 @@
 
 #define MEASUREMENT_IDX_PEAK 0
 #define MEASUREMENT_IDX_RMS  1
+#define MEASUREMENT_COUNT 2
 
 /* enumerated parameters for Visualizer effect */
 typedef enum