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

This patch corrects the SPDX License Identifier style in
header files related to USB peripheral 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>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/gadget/function/f_uvc.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  *	f_uvc.h  --  USB Video Class Gadget driver
  *

drivers/usb/gadget/function/rndis.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * RNDIS	Definitions for Remote NDIS
  *

drivers/usb/gadget/function/u_audio.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * u_audio.h -- interface to USB gadget "ALSA sound card" utilities
  *

drivers/usb/gadget/function/u_ecm.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_ecm.h
  *

drivers/usb/gadget/function/u_eem.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_eem.h
  *

drivers/usb/gadget/function/u_ether.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * u_ether.h -- interface to USB gadget "ethernet link" utilities
  *

drivers/usb/gadget/function/u_ether_configfs.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_ether_configfs.h
  *

drivers/usb/gadget/function/u_fs.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_fs.h
  *

drivers/usb/gadget/function/u_gether.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_gether.h
  *

drivers/usb/gadget/function/u_hid.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_hid.h
  *

drivers/usb/gadget/function/u_midi.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_midi.h
  *

drivers/usb/gadget/function/u_ncm.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_ncm.h
  *

drivers/usb/gadget/function/u_phonet.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * u_phonet.h - interface to Phonet
  *

drivers/usb/gadget/function/u_printer.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_printer.h
  *

drivers/usb/gadget/function/u_rndis.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_rndis.h
  *

drivers/usb/gadget/function/u_serial.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * u_serial.h - interface to USB gadget "serial port"/TTY utilities
  *

drivers/usb/gadget/function/u_tcm.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_tcm.h
  *

drivers/usb/gadget/function/u_uac1.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_uac1.h - Utility definitions for UAC1 function
  *

drivers/usb/gadget/function/u_uac1_legacy.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * u_uac1.h -- interface to USB gadget "ALSA AUDIO" utilities
  *

drivers/usb/gadget/function/u_uac2.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_uac2.h
  *

drivers/usb/gadget/function/u_uvc.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * u_uvc.h
  *

drivers/usb/gadget/function/uvc.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  *	uvc_gadget.h  --  USB Video Class Gadget driver
  *

drivers/usb/gadget/function/uvc_configfs.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * uvc_configfs.h
  *

drivers/usb/gadget/function/uvc_v4l2.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *	uvc_v4l2.h  --  USB Video Class Gadget driver
  *

drivers/usb/gadget/function/uvc_video.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  *	uvc_video.h  --  USB Video Class Gadget driver
  *