Add GPL-2.0+ SPDX-License-Identifier to source files

Signed-off-by: Wolfgang Denk <wd@denx.de>
[trini: Fixup common/cmd_io.c]
Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/drivers/net/smc91111.c b/drivers/net/smc91111.c
index 1357ede..57c667a 100644
--- a/drivers/net/smc91111.c
+++ b/drivers/net/smc91111.c
@@ -10,19 +10,7 @@
  .	 Developed by Simple Network Magic Corporation (SNMC)
  . Copyright (C) 1996 by Erik Stahlman (ES)
  .
- . This program is free software; you can redistribute it and/or modify
- . it under the terms of the GNU General Public License as published by
- . the Free Software Foundation; either version 2 of the License, or
- . (at your option) any later version.
- .
- . This program 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 General Public License for more details.
- .
- . You should have received a copy of the GNU General Public License
- . along with this program; if not, write to the Free Software
- . Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307	 USA
+ * SPDX-License-Identifier:	GPL-2.0+
  .
  . Information contained in this file was obtained from the LAN91C111
  . manual from SMC.  To get a copy, if you really want one, you can find