nozomi: simplify ntty_chars_in_buffer

ntty_chars_in_buffer is overly complicated. Simplify it by inverting the
condition.

Side FIXME: how can dc or port be NULL here?
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210505091928.22010-29-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/nozomi.c

@@ -1780,16 +1780,11 @@ static unsigned int ntty_chars_in_buffer(struct tty_struct *tty)
 {
 	struct port *port = tty->driver_data;
 	struct nozomi *dc = get_dc_by_tty(tty);
-	s32 rval = 0;
 
-	if (unlikely(!dc || !port)) {
-		goto exit_in_buffer;
-	}
-
-	rval = kfifo_len(&port->fifo_ul);
+	if (unlikely(!dc || !port))
+		return 0;
 
-exit_in_buffer:
-	return rval;
+	return kfifo_len(&port->fifo_ul);
 }
 
 static const struct tty_port_operations noz_tty_port_ops = {