Add LGPL-2.1+ SPDX-License-Identifier to source files

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/include/libfdt_env.h b/include/libfdt_env.h
index 0821258..273b5d3 100644
--- a/include/libfdt_env.h
+++ b/include/libfdt_env.h
@@ -3,19 +3,7 @@
  * Copyright (C) 2007 Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com
  * Original version written by David Gibson, IBM Corporation.
  *
- * 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 2.1 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
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ * SPDX-License-Identifier:	LGPL-2.1+
  */
 
 #ifndef _LIBFDT_ENV_H