Add missing copyright header to STM32 driver

Author: Seppo Takalo

features/netsocket/emac-drivers/TARGET_STM_EMAC/stm32xx_emac.cpp

@@ -1,3 +1,19 @@
+/* Copyright (c) 2017 ARM Limited
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 #include <stdlib.h>
 
 #include "cmsis_os.h"

features/netsocket/emac-drivers/TARGET_STM_EMAC/stm32xx_emac_config.h

@@ -1,4 +1,5 @@
 /* Copyright (c) 2017 ARM Limited
+ * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.