can: rcar: use SPDX identifier for Renesas drivers

Adopt the SPDX license identifier headers to ease license compliance
management.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/rcar/rcar_can.c

+// SPDX-License-Identifier: GPL-2.0+
 /* Renesas R-Car CAN device driver
  *
  * Copyright (C) 2013 Cogent Embedded, Inc. <source@cogentembedded.com>
  * Copyright (C) 2013 Renesas Solutions Corp.
- *
- * 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;  either version 2 of the  License, or (at your
- * option) any later version.
  */
 
 #include <linux/module.h>

drivers/net/can/rcar/rcar_canfd.c

+// SPDX-License-Identifier: GPL-2.0+
 /* Renesas R-Car CAN FD device driver
  *
  * Copyright (C) 2015 Renesas Electronics Corp.
- *
- * 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;  either version 2 of the  License, or (at your
- * option) any later version.
  */
 
 /* The R-Car CAN FD controller can operate in either one of the below two modes