USB: host: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style in
header files related to USB host 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.
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Link: https://lore.kernel.org/r/20200404092135.GA4522@nishadSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-fsl.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /* Copyright (C) 2005-2010,2012 Freescale Semiconductor, Inc.
  * Copyright (c) 2005 MontaVista Software
  */

drivers/usb/host/ehci.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Copyright (c) 2001-2002 by David Brownell
  */

drivers/usb/host/fhci.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Freescale QUICC Engine USB Host Controller Driver
  *

drivers/usb/host/imx21-hcd.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Macros and prototypes for i.MX21
  *

drivers/usb/host/ohci.h

-// SPDX-License-Identifier: GPL-1.0+
+/* SPDX-License-Identifier: GPL-1.0+ */
 /*
  * OHCI HCD (Host Controller Driver) for USB.
  *

drivers/usb/host/r8a66597.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * R8A66597 HCD (Host Controller Driver)
  *

drivers/usb/host/xhci-debugfs.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * xhci-debugfs.h - xHCI debugfs interface
  *

drivers/usb/host/xhci-ext-caps.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * xHCI host controller driver
  *

drivers/usb/host/xhci-mtk.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (c) 2015 MediaTek Inc.
  * Author:

drivers/usb/host/xhci-mvebu.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2014 Marvell
  *

drivers/usb/host/xhci-plat.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * xhci-plat.h - xHCI host controller driver platform Bus Glue.
  *

drivers/usb/host/xhci-rcar.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * drivers/usb/host/xhci-rcar.h
  *

drivers/usb/host/xhci-trace.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * xHCI host controller driver
  *

drivers/usb/host/xhci.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 
 /*
  * xHCI host controller driver