boards/risk-v/sg2000: migrate to SPDX identifier

Most tools used for compliance and SBOM generation use SPDX identifiers
This change brings us a step closer to an easy SBOM generation.

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>

boards/risc-v/sg2000/milkv_duos/include/board.h

@@ -1,6 +1,8 @@
 /****************************************************************************
  * boards/risc-v/sg2000/milkv_duos/include/board.h
  *
+ * SPDX-License-Identifier: Apache-2.0
+ *
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.  The

boards/risc-v/sg2000/milkv_duos/include/board_memorymap.h

@@ -1,6 +1,8 @@
 /****************************************************************************
  * boards/risc-v/sg2000/milkv_duos/include/board_memorymap.h
  *
+ * SPDX-License-Identifier: Apache-2.0
+ *
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.  The

boards/risc-v/sg2000/milkv_duos/scripts/Make.defs

@@ -1,6 +1,8 @@
 ############################################################################
 # boards/risc-v/sg2000/milkv_duos/scripts/Make.defs
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

boards/risc-v/sg2000/milkv_duos/scripts/ld.script

@@ -1,6 +1,8 @@
 /****************************************************************************
  * boards/risc-v/sg2000/milkv_duos/scripts/ld.script
  *
+ * SPDX-License-Identifier: Apache-2.0
+ *
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.  The

boards/risc-v/sg2000/milkv_duos/src/Makefile

@@ -1,6 +1,8 @@
 ############################################################################
 # boards/risc-v/sg2000/milkv_duos/src/Makefile
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

boards/risc-v/sg2000/milkv_duos/src/etc/init.d/rc.sysinit

@@ -1,6 +1,8 @@
 /****************************************************************************
  * boards/risc-v/sg2000/milkv_duos/src/etc/init.d/rc.sysinit
  *
+ * SPDX-License-Identifier: Apache-2.0
+ *
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.  The

boards/risc-v/sg2000/milkv_duos/src/etc/init.d/rcS

@@ -1,6 +1,8 @@
 /****************************************************************************
  * boards/risc-v/sg2000/milkv_duos/src/etc/init.d/rcS
  *
+ * SPDX-License-Identifier: Apache-2.0
+ *
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.  The

boards/risc-v/sg2000/milkv_duos/src/sg2000_appinit.c

@@ -1,6 +1,8 @@
 /****************************************************************************
  * boards/risc-v/sg2000/milkv_duos/src/sg2000_appinit.c
  *
+ * SPDX-License-Identifier: Apache-2.0
+ *
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.  The