Update assembly Copyright notice to // comment

PiperOrigin-RevId: 275581634
diff --git a/src/f32-gemm/5x8-aarch64-neonfma-cortex-a75.S b/src/f32-gemm/5x8-aarch64-neonfma-cortex-a75.S
index d6014d9..53e6ea1 100644
--- a/src/f32-gemm/5x8-aarch64-neonfma-cortex-a75.S
+++ b/src/f32-gemm/5x8-aarch64-neonfma-cortex-a75.S
@@ -2,10 +2,10 @@
 //   Template: src/f32-gemm/5x8-aarch64-neonfma-cortex-a75.S.in
 //   Generator: tools/xngen
 //
-# Copyright 2019 Google LLC
-#
-# This source code is licensed under the BSD-style license found in the
-# LICENSE file in the root directory of this source tree.
+// Copyright 2019 Google LLC
+//
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree.
 
 #include <xnnpack/assembly.h>