s390: kernel: add SPDX identifiers to the remaining files

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the arch/s390/kernel/ files with the correct SPDX license
identifier based on the license text in the file itself.  The SPDX
identifier is a legally binding shorthand, which can be used instead of
the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/dis.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Disassemble s390 instructions.
  *

arch/s390/kernel/dumpstack.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Stack dumping functions
  *

arch/s390/kernel/ipl.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *    ipl/reipl/dump support for Linux on s390.
  *

arch/s390/kernel/kprobes.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  *  Kernel Probes (KProbes)
  *

arch/s390/kernel/lgr.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Linux Guest Relocation (LGR) detection
  *

arch/s390/kernel/module.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  *  Kernel module help for s390.
  *

arch/s390/kernel/nmi.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *   Machine check handler
  *

arch/s390/kernel/perf_cpum_cf.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Performance event support for s390x - CPU-measurement Counter Facility
  *

arch/s390/kernel/perf_cpum_sf.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Performance event support for the System z CPU-measurement Sampling Facility
  *

arch/s390/kernel/perf_event.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Performance event support for s390x
  *

arch/s390/kernel/setup.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *  S390 version
  *    Copyright IBM Corp. 1999, 2012

arch/s390/kernel/stacktrace.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Stack trace management functions
  *

arch/s390/kernel/time.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *    Time of day based timer functions.
  *

arch/s390/kernel/topology.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *    Copyright IBM Corp. 2007, 2011
  *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>

arch/s390/kernel/vdso.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * vdso setup for s390
  *

arch/s390/kernel/vdso32/clock_getres.S

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Userland implementation of clock_getres() for 32 bits processes in a
  * s390 kernel for use in the vDSO

arch/s390/kernel/vdso32/clock_gettime.S

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Userland implementation of clock_gettime() for 32 bits processes in a
  * s390 kernel for use in the vDSO

arch/s390/kernel/vdso32/gettimeofday.S

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Userland implementation of gettimeofday() for 32 bits processes in a
  * s390 kernel for use in the vDSO

arch/s390/kernel/vdso64/clock_getres.S

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Userland implementation of clock_getres() for 64 bits processes in a
  * s390 kernel for use in the vDSO

arch/s390/kernel/vdso64/clock_gettime.S

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Userland implementation of clock_gettime() for 64 bits processes in a
  * s390 kernel for use in the vDSO

arch/s390/kernel/vdso64/gettimeofday.S

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Userland implementation of gettimeofday() for 64 bits processes in a
  * s390 kernel for use in the vDSO

arch/s390/kernel/vtime.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  *    Virtual cpu timer based timer functions.
  *