ocxl: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style
in header files for Open Coherent Accelerator (OCXL) compatible 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: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Acked-by: Andrew Donnellan <ajd@linux.ibm.com>
Link: https://lore.kernel.org/r/20190920161826.GA6894@nishadSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/ocxl/ocxl_internal.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright 2017 IBM Corp.
 #ifndef _OCXL_INTERNAL_H_
 #define _OCXL_INTERNAL_H_

drivers/misc/ocxl/trace.h

-// SPDX-License-Identifier: GPL-2.0+
+/* SPDX-License-Identifier: GPL-2.0+ */
 // Copyright 2017 IBM Corp.
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM ocxl