usb: renesas_usbhs: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style in
header files related to Renesas USBHS Controller Drivers.
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.
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/renesas_usbhs/common.h

-// SPDX-License-Identifier: GPL-1.0+
+/* SPDX-License-Identifier: GPL-1.0+ */
 /*
  * Renesas USB driver
  *

drivers/usb/renesas_usbhs/fifo.h

-// SPDX-License-Identifier: GPL-1.0+
+/* SPDX-License-Identifier: GPL-1.0+ */
 /*
  * Renesas USB driver
  *

drivers/usb/renesas_usbhs/mod.h

-// SPDX-License-Identifier: GPL-1.0+
+/* SPDX-License-Identifier: GPL-1.0+ */
 /*
  * Renesas USB driver
  *

drivers/usb/renesas_usbhs/pipe.h

-// SPDX-License-Identifier: GPL-1.0+
+/* SPDX-License-Identifier: GPL-1.0+ */
 /*
  * Renesas USB driver
  *

drivers/usb/renesas_usbhs/rcar2.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 #include "common.h"
 
 extern const struct renesas_usbhs_platform_info usbhs_rcar_gen2_plat_info;

drivers/usb/renesas_usbhs/rcar3.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 #include "common.h"
 
 extern const struct renesas_usbhs_platform_info usbhs_rcar_gen3_plat_info;

drivers/usb/renesas_usbhs/rza.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 #include "common.h"
 
 extern const struct renesas_usbhs_platform_info usbhs_rza1_plat_info;