net: dsa: microchip: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style
in header files related to Distributed Switch Architecture
drivers for Microchip KSZ series switch support.
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/dsa/microchip/ksz9477_reg.h

-/* SPDX-License-Identifier: GPL-2.0
- *
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
  * Microchip KSZ9477 register definitions
  *
  * Copyright (C) 2017-2018 Microchip Technology Inc.

drivers/net/dsa/microchip/ksz_common.h

-/* SPDX-License-Identifier: GPL-2.0
- * Microchip switch driver common header
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Microchip switch driver common header
  *
  * Copyright (C) 2017-2019 Microchip Technology Inc.
  */