virtio_console: Get rid of unneeded temporary variable

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 <andriy.shevchenko@linux.intel.com>
Reviewed-by: Amit Shah <amit@kernel.org>
Link: https://lore.kernel.org/r/20250210095946.4122771-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>