Further reduce number of uniforms in UniformsBenchmark.Run/gles_matrix

Because Perf bots have Android K with worse driver than GPU.FYI Android L

BUG=angleproject:2431

Change-Id: I9b7a7d34f64a9832c57f9d26573b7c63594e1773
Reviewed-on: https://chromium-review.googlesource.com/986653
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>

Author: y-novikov

src/tests/perf_tests/UniformsPerf.cpp

@@ -396,8 +396,8 @@ UniformsParams MatrixUniforms(const EGLPlatformParameters &egl, DataMode dataMod
     params.dataMode      = dataMode;
 
     // Reduce the number of uniforms to fit within smaller upper limits on some configs.
-    params.numVertexUniforms   = 56;
-    params.numFragmentUniforms = 56;
+    params.numVertexUniforms   = 55;
+    params.numFragmentUniforms = 55;
 
     return params;
 }