target/s390x: Fix LGPL version in the file header comments

It's either "GNU *Library* General Public License version 2" or
"GNU Lesser General Public License version *2.1*", but there was
no "version 2.0" of the "Lesser" license. So assume that version
2.1 is meant here.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <1548769067-20792-1-git-send-email-thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
diff --git a/target/s390x/helper.c b/target/s390x/helper.c
index 2546316..3d74836 100644
--- a/target/s390x/helper.c
+++ b/target/s390x/helper.c
@@ -7,7 +7,7 @@
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
+ * version 2.1 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of