tty: fix up a few remaining files without SPDX identifiers

There were a few straggling files under drivers/tty/ that did not have
any SPDX identifier either because they entered the tree recently, or
they somehow missed the mass-tagging of commit b2441318 ("License
cleanup: add SPDX GPL-2.0 license identifier to files with no license")

This commit follows the same rule as b2441318 ("License cleanup: add
SPDX GPL-2.0 license identifier to files with no license") where files
without any specified license in them fall under GPL-2.0 as the correct
license for the individual file.  Add that identifier to these remaining
files so that we don't have to guess at the license of them in the
future.

Cc: Jiri Slaby <jslaby@suse.com>
Cc: "David S. Miller" <davem@davemloft.net>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_men_mcb.c

+// SPDX-License-Identifier: GPL-2.0
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/module.h>

drivers/tty/serial/sn_console.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * C-Brick Serial Port (and console) driver for SGI Altix machines.
  *

drivers/tty/vcc.c

+// SPDX-License-Identifier: GPL-2.0
 /* vcc.c: sun4v virtual channel concentrator
  *
  * Copyright (C) 2017 Oracle. All rights reserved.

drivers/tty/vt/.gitignore

+# SPDX-License-Identifier: GPL-2.0
 consolemap_deftbl.c
 defkeymap.c

drivers/tty/vt/cp437.uni

+# SPDX-License-Identifier: GPL-2.0
 #
 # Unicode table for IBM Codepage 437.  Note that there are many more
 # substitutions that could be conceived (for example, thick-line

drivers/tty/vt/defkeymap.c_shipped

+// SPDX-License-Identifier: GPL-2.0
 /* Do not edit this file! It was automatically generated by   */
 /*    loadkeys --mktable defkeymap.map > defkeymap.c          */
 

drivers/tty/vt/defkeymap.map

+# SPDX-License-Identifier: GPL-2.0
 # Default kernel keymap. This uses 7 modifier combinations.
 keymaps 0-2,4-5,8,12
 # Change the above line into