target/m68k: Fix LGPL information in the file headers

target/m68k: Fix LGPL information in the file headers

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.
Also some files mention the GPL instead of the LGPL after declaring
that the files are licensed under the LGPL, so change these spots to
use LGPL, too.

Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1548769438-28942-1-git-send-email-thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>