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

This patch corrects the SPDX License Identifier style
in header file related to Siano Mobile Silicon Digital TV.
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/2019/2/7/46Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/common/siano/smsir.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
- * SPDX-License-Identifier: GPL-2.0+
  *
  * Siano Mobile Silicon, Inc.
  * MDTV receiver kernel modules.