firmware: set license to GPLv2+

Change-Id: Id4c00159f984976b6d8641900fb64e36a3a30407
diff --git a/firmware/libboard/common/source/led.c b/firmware/libboard/common/source/led.c
index 00082e2..cffff70 100644
--- a/firmware/libboard/common/source/led.c
+++ b/firmware/libboard/common/source/led.c
@@ -1,3 +1,22 @@
+/* LED control
+ *
+ * (C) 2015-2017 by Harald Welte <hwelte@hmw-consulting.de>
+ * (C) 2018 by sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
+ *
+ * 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
+ */
 #include <stdint.h>
 #include <string.h>
 #include <assert.h>