net: hns3: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style in
header files related to Hisilicon network devices. For C header files
Documentation/process/license-rules.rst mandates C-like comments
(opposed to C source files where C++ style should be used)

Changes made by using a script provided by Joe Perches here:
https://lkml.org/lkml/2019/2/7/46.
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hnae3.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright (c) 2016-2017 Hisilicon Limited.
 
 #ifndef __HNAE3_H

drivers/net/ethernet/hisilicon/hns3/hns3_enet.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright (c) 2016-2017 Hisilicon Limited.
 
 #ifndef __HNS3_ENET_H

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_cmd.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright (c) 2016-2017 Hisilicon Limited.
 
 #ifndef __HCLGE_CMD_H

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_dcb.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright (c) 2016-2017 Hisilicon Limited.
 
 #ifndef __HCLGE_DCB_H__

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright (c) 2016-2017 Hisilicon Limited.
 
 #ifndef __HCLGE_MAIN_H

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mdio.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright (c) 2016-2017 Hisilicon Limited.
 
 #ifndef __HCLGE_MDIO_H

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_tm.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright (c) 2016-2017 Hisilicon Limited.
 
 #ifndef __HCLGE_TM_H