staging: comedi: drivers: Cleanup malformed licence identifier

This patch fixes multiple occurences of the checkpatch.pl warning:
WARNING: Missing or malformed SPDX-License-Identifier tag in line 1

NB. This is an additional patch and does not overlap the patch sent
yesterday for 8255.h. Should have sent them all together.
Newb mistake.

Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Stephen Davies <davo2002@tpg.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/amplc_dio200.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * comedi/drivers/amplc_dio.h
  *

drivers/staging/comedi/drivers/amplc_pc236.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * comedi/drivers/amplc_pc236.h
  * Header for "amplc_pc236", "amplc_pci236" and "amplc_pc236_common".

drivers/staging/comedi/drivers/comedi_8254.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * comedi_8254.h
  * Generic 8254 timer/counter support

drivers/staging/comedi/drivers/comedi_isadma.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * COMEDI ISA DMA support functions
  * Copyright (c) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>

drivers/staging/comedi/drivers/das08.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * das08.h
  *

drivers/staging/comedi/drivers/mite.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * module/mite.h
  * Hardware driver for NI Mite PCI interface chip

drivers/staging/comedi/drivers/ni_labpc.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Header for ni_labpc ISA/PCMCIA/PCI drivers
  *

drivers/staging/comedi/drivers/ni_stc.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Register descriptions for NI DAQ-STC chip
  *

drivers/staging/comedi/drivers/ni_tio.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Header file for NI general purpose counter support code (ni_tio.c)
  *

drivers/staging/comedi/drivers/ni_tio_internal.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Header file for NI general purpose counter support code (ni_tio.c and
  * ni_tiocmd.c)

drivers/staging/comedi/drivers/plx9052.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Definitions for the PLX-9052 PCI interface chip
  *

drivers/staging/comedi/drivers/plx9080.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * plx9080.h
  *

drivers/staging/comedi/drivers/s626.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * comedi/drivers/s626.h
  * Sensoray s626 Comedi driver, header file