virtio_console: Get rid of unneeded temporary variable

When compiling a kernel with GCC using `make W=1` with CONFIG_WERROR=y
(which is default nowadays), the build fails:

drivers/char/virtio_console.c:1427:9: note: ‘snprintf’ output between 9 and 27 bytes into a destination of size 16

Indeed, GCC can't see the limits of the variables that are in use.
Fix this by using dev_name() of the newly created device that is
luckily the same as the string used for the DebugFS node name.

Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Amit Shah <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/char/virtio_console.c

···
 
 static int add_port(struct ports_device *portdev, u32 id)
 {
-	char debugfs_name[16];
 	struct port *port;
 	dev_t devt;
 	int err;
···
 	 * Finally, create the debugfs file that we can use to
 	 * inspect a port's state at any time
 	 */
-	snprintf(debugfs_name, sizeof(debugfs_name), "vport%up%u",
-		 port->portdev->vdev->index, id);
-	port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
+	port->debugfs_file = debugfs_create_file(dev_name(port->dev), 0444,
 						 pdrvdata.debugfs_dir,
 						 port, &port_debugfs_fops);
 	return 0;