sti: fix STMicroelectronics copyright

Uniformize all STMicroelectronics copyrights headers for STi
related code.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/drivers/serial/serial_sti_asc.c b/drivers/serial/serial_sti_asc.c
index 8dcd4f8..00773cc 100644
--- a/drivers/serial/serial_sti_asc.c
+++ b/drivers/serial/serial_sti_asc.c
@@ -1,10 +1,10 @@
 /*
  * Support for Serial I/O using STMicroelectronics' on-chip ASC.
  *
- *  Copyright (c) 2017
- *  Patrice Chotard <patrice.chotard@st.com>
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Author(s): Patrice Chotard, <patrice.chotard@st.com> for STMicroelectronics.
  *
- * SPDX-License-Identifier:	GPL-2.0
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>