serial: stm32: fix copyright

Fix missing copyright for STMicroelectronics
Signed-off-by: Bich Hemon <bich.hemon@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/stm32-usart.c

 /*
  * Copyright (C) Maxime Coquelin 2015
+ * Copyright (C) STMicroelectronics SA 2017
  * Authors:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
  *	     Gerald Baeza <gerald.baeza@st.com>
  * License terms:  GNU General Public License (GPL), version 2

drivers/tty/serial/stm32-usart.h

 /*
  * Copyright (C) Maxime Coquelin 2015
+ * Copyright (C) STMicroelectronics SA 2017
  * Authors:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
  *	     Gerald Baeza <gerald_baeza@yahoo.fr>
  * License terms:  GNU General Public License (GPL), version 2