tty/vt: Makefile, add --unicode for loadkeys invocation

For a long time, we generate unicode tables using loadkeys. So fix
Makefile to use that flag too.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220602083128.22540-2-jslaby@suse.cz


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>