gpu: nvgpu: remove SPDX license identifier from hal

Below change added SPDX license identifier as svcacv complained.
However, these files have MIT license. SPDX need to be added to
GPL licensed sources.

  commit 2b2beb7fb6 ("gpu: nvgpu: ga10b: restore the ptimer isr hal")

Remove the identifier from hal files.

Change-Id: Ic90c46721d06a43749e5a48f7077a837a96fb664
Signed-off-by: Sagar Kamble <skamble@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2770085
Reviewed-by: Vaibhav Kachore <vkachore@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>

drivers/gpu/nvgpu/hal/ptimer/ptimer_ga10b.h

@@ -1,4 +1,3 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (c) 2020-2022, NVIDIA CORPORATION.  All rights reserved.
  *

drivers/gpu/nvgpu/hal/ptimer/ptimer_ga10b_fusa.c

@@ -1,4 +1,3 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (c) 2020-2022, NVIDIA CORPORATION.  All rights reserved.
  *