treewide: Add SPDX license identifier for more missed files

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have MODULE_LICENCE("GPL*") inside which was used in the initial
   scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/cpufreq/ia64-acpi-cpufreq.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * This file provides the ACPI based P-state support. This
  * module works with generic cpufreq infrastructure. Most of

drivers/cpufreq/sparc-us2e-cpufreq.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /* us2e_cpufreq.c: UltraSPARC-IIe cpu frequency support
  *
  * Copyright (C) 2003 David S. Miller (davem@redhat.com)

drivers/cpufreq/sparc-us3-cpufreq.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /* us3_cpufreq.c: UltraSPARC-III cpu frequency support
  *
  * Copyright (C) 2003 David S. Miller (davem@redhat.com)

drivers/cpufreq/speedstep-centrino.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * cpufreq driver for Enhanced SpeedStep, as found in Intel's Pentium
  * M (part of the Centrino chipset).