tty: Fix direct use of tty buffer work

Recent abstraction of tty buffer work introduced api to manage
tty input kworker; use it.

Fixes: e176058f0de5 ("tty: Abstract tty buffer work")
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_ldisc.c

@@ -592,7 +592,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
 	/* Restart the work queue in case no characters kick it off. Safe if
 	   already running */
-	schedule_work(&tty->port->buf.work);
+	tty_buffer_restart_work(tty->port);
 
 	tty_unlock(tty);
 	return retval;