n_tty: check printk arguments for n_tty_trace

When N_TTY_TRACE is undefined (the default), define n_tty_trace to use
no_printk. That way, arguments are still checked during compilation.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200130115843.7452-1-jslaby@suse.cz


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