Tweak threshold for PSNR test for gf frames

BUG=aomedia:2490

Change-Id: Ibe9c3fa178b823b59c0fc0dc6dc821e3bffb7f80
diff --git a/test/gf_max_pyr_height_test.cc b/test/gf_max_pyr_height_test.cc
index 92cec31..1942bd2 100644
--- a/test/gf_max_pyr_height_test.cc
+++ b/test/gf_max_pyr_height_test.cc
@@ -21,7 +21,7 @@
   int gf_max_pyr_height;
   double psnr_thresh;
 } kTestParams[] = {
-  { 0, 34.4 }, { 1, 34.50 }, { 2, 35.09 }, { 3, 35.35 }, { 4, 35.50 },
+  { 0, 34.4 }, { 1, 34.50 }, { 2, 35.0 }, { 3, 35.35 }, { 4, 35.50 },
 };
 
 // Compiler may decide to add some padding to the struct above for alignment,