tty_port: Fix return on interrupted use

Whoops.. fortunately not many people use this yet.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/tty_port.c

@@ -267,7 +267,7 @@ int tty_port_block_til_ready(struct tty_port *port,
 	if (retval == 0)
 		port->flags |= ASYNC_NORMAL_ACTIVE;
 	spin_unlock_irqrestore(&port->lock, flags);
-	return 0;
+	return retval;
 	
 }
 EXPORT_SYMBOL(tty_port_block_til_ready);