misc: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style
in header files for Miscellaneous device 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: NJoe Perches <joe@perches.com>
Signed-off-by: NNishad Kamdar <nishadkamdar@gmail.com>
Link: https://lore.kernel.org/r/20190920155931.GA6251@nishadSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/hpilo.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * linux/drivers/char/hpilo.h
  *

drivers/misc/ibmvmc.h

-/* SPDX-License-Identifier: GPL-2.0+
- *
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
  * linux/drivers/misc/ibmvmc.h
  *
  * IBM Power Systems Virtual Management Channel Support.