media: i2c: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style
in header files related to I2C controlled media codec 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
and some manual changes.

Suggested-by: Joe Perches <[e-mail]>
Signed-off-by: Nishad Kamdar <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/i2c/max2175.h

···
-/* SPDX-License-Identifier: GPL-2.0
- *
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
  * Maxim Integrated MAX2175 RF to Bits tuner driver
  *
  * This driver & most of the hard coded values are based on the reference

drivers/media/i2c/saa711x_regs.h

···
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
- * SPDX-License-Identifier: GPL-2.0+
  * saa711x - Philips SAA711x video decoder register specifications
  *
  * Copyright (c) 2006 Mauro Carvalho Chehab <[e-mail]>

drivers/media/i2c/tda1997x_regs.h

···
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2018 Gateworks Corporation
  */

drivers/media/i2c/tvp5150_reg.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
- * SPDX-License-Identifier: GPL-2.0
  *
  * tvp5150 - Texas Instruments TVP5150A/AM1 video decoder registers
  *