Fix some more license versions (GPL2+ instead of GPL2)

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
diff --git a/memory_mapping-stub.c b/memory_mapping-stub.c
index 104281d..76be34d 100644
--- a/memory_mapping-stub.c
+++ b/memory_mapping-stub.c
@@ -6,8 +6,8 @@
  * Authors:
  *     Wen Congyang <wency@cn.fujitsu.com>
  *
- * This work is licensed under the terms of the GNU GPL, version 2. See
- * the COPYING file in the top-level directory.
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
  *
  */
 
diff --git a/memory_mapping.c b/memory_mapping.c
index 1125e3f..6f5a2e3 100644
--- a/memory_mapping.c
+++ b/memory_mapping.c
@@ -6,8 +6,8 @@
  * Authors:
  *     Wen Congyang <wency@cn.fujitsu.com>
  *
- * This work is licensed under the terms of the GNU GPL, version 2. See
- * the COPYING file in the top-level directory.
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
  *
  */
 
diff --git a/memory_mapping.h b/memory_mapping.h
index 3f00358..ef72b0a 100644
--- a/memory_mapping.h
+++ b/memory_mapping.h
@@ -6,8 +6,8 @@
  * Authors:
  *     Wen Congyang <wency@cn.fujitsu.com>
  *
- * This work is licensed under the terms of the GNU GPL, version 2. See
- * the COPYING file in the top-level directory.
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
  *
  */
 
diff --git a/target-i386/arch_dump.c b/target-i386/arch_dump.c
index 7c2b514..4240278 100644
--- a/target-i386/arch_dump.c
+++ b/target-i386/arch_dump.c
@@ -6,8 +6,8 @@
  * Authors:
  *     Wen Congyang <wency@cn.fujitsu.com>
  *
- * This work is licensed under the terms of the GNU GPL, version 2.  See
- * the COPYING file in the top-level directory.
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
  *
  */
 
diff --git a/target-i386/arch_memory_mapping.c b/target-i386/arch_memory_mapping.c
index efb0211..8e5a56a 100644
--- a/target-i386/arch_memory_mapping.c
+++ b/target-i386/arch_memory_mapping.c
@@ -6,8 +6,8 @@
  * Authors:
  *     Wen Congyang <wency@cn.fujitsu.com>
  *
- * This work is licensed under the terms of the GNU GPL, version 2.  See
- * the COPYING file in the top-level directory.
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
  *
  */