treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 78

Based on 1 normalized pattern(s):

  this work is licensed under the terms of the gnu gpl version 2 or
  later see the copying file in the top level directory

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 6 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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/20190520075210.858783702@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/virtio/virtio_mmio.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Virtio memory mapped device driver
  *
@@ -48,12 +49,7 @@
  *		virtio_mmio.device=0x100@0x100b0000:48 \
  *				virtio_mmio.device=1K@0x1001e000:74
  *
- *
- *
  * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
- *
- * This work is licensed under the terms of the GNU GPL, version 2 or later.
- * See the COPYING file in the top-level directory.
  */
 
 #define pr_fmt(fmt) "virtio-mmio: " fmt