can: flexcan: Switch to SPDX identifier

Adopt the SPDX license identifier headers to ease license compliance
management.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/flexcan.c

-/*
- * flexcan.c - FLEXCAN CAN controller driver
- *
- * Copyright (c) 2005-2006 Varma Electronics Oy
- * Copyright (c) 2009 Sascha Hauer, Pengutronix
- * Copyright (c) 2010-2017 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
- * Copyright (c) 2014 David Jander, Protonic Holland
- *
- * Based on code originally by Andrey Volkov <avolkov@varma-el.com>
- *
- * LICENCE:
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation version 2.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- */
+// SPDX-License-Identifier: GPL-2.0
+//
+// flexcan.c - FLEXCAN CAN controller driver
+//
+// Copyright (c) 2005-2006 Varma Electronics Oy
+// Copyright (c) 2009 Sascha Hauer, Pengutronix
+// Copyright (c) 2010-2017 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
+// Copyright (c) 2014 David Jander, Protonic Holland
+//
+// Based on code originally by Andrey Volkov <avolkov@varma-el.com>
 
 #include <linux/netdevice.h>
 #include <linux/can.h>