Fix potential NULL dereference in Visualizer effect

Bug: 30229821

Test: fixing CL. Existing unit tests still pass.

Change-Id: I73d3fe413dd7590470c5b3b19569d6a7969c4dd8
(cherry picked from commit 0c39abc483ba980f7c417e57a0aa39139136c97a)
1 file changed
tree: de58a2fd7fb6dc940c71f080a8a331c9810976f7
  1. hal/
  2. legacy/
  3. msm8909/
  4. post_proc/
  5. visualizer/
  6. voice_processing/
  7. Android.mk