treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 198

Based on 1 normalized pattern(s):

  this software may be distributed under the terms of the gnu general
  public license gpl version 2 as distributed in the copying file from
  the main directory of the linux kernel source

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 1 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528170027.816396794@linutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/can/at91_can.c

+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * at91_can.c - CAN network driver for AT91 SoC CAN controller
  *
  * (C) 2007 by Hans J. Koch <hjk@hansjkoch.de>
  * (C) 2008, 2009, 2010, 2011 by Marc Kleine-Budde <kernel@pengutronix.de>
- *
- * This software may be distributed under the terms of the GNU General
- * Public License ("GPL") version 2 as distributed in the 'COPYING'
- * file from the main directory of the linux kernel source.
- *
  */
 
 #include <linux/clk.h>