sf: Add GPL-2.0+ SPDX-License-Identifier for missing ones

Added GPL-2.0+ SPDX-License-Identifier for missed sf
source files.

Signed-off-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
Signed-off-by: Bo Shen <voice.shen@atmel.com>

common/cmd_sf.c

@@ -2,7 +2,8 @@
  * Command for accessing SPI flash.
  *
  * Copyright (C) 2008 Atmel Corporation
- * Licensed under the GPL-2 or later.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>

drivers/mtd/spi/sf.c

@@ -4,7 +4,7 @@
  * Copyright (C) 2008 Atmel Corporation
  * Copyright (C) 2010 Reinhard Meyer, EMK Elektronik
  *
- * Licensed under the GPL-2 or later.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>

drivers/mtd/spi/sf_internal.h

@@ -4,7 +4,7 @@
  * Copyright (C) 2008 Atmel Corporation
  * Copyright (C) 2013 Jagannadha Sutradharudu Teki, Xilinx Inc.
  *
- * Licensed under the GPL-2 or later.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #ifndef _SF_INTERNAL_H_

drivers/mtd/spi/sf_ops.c

@@ -5,7 +5,7 @@
  * Copyright (C) 2010 Reinhard Meyer, EMK Elektronik
  * Copyright (C) 2013 Jagannadha Sutradharudu Teki, Xilinx Inc.
  *
- * Licensed under the GPL-2 or later.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>

drivers/mtd/spi/sf_probe.c

@@ -5,7 +5,7 @@
  * Copyright (C) 2010 Reinhard Meyer, EMK Elektronik
  * Copyright (C) 2013 Jagannadha Sutradharudu Teki, Xilinx Inc.
  *
- * Licensed under the GPL-2 or later.
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>