tty: remove sleep_on

Use wait_event instead of sleep_on in tty_block_til_ready.

Wait for ASYNC_CLOSING flag being 0.
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/tty_port.c

@@ -198,7 +198,8 @@ int tty_port_block_til_ready(struct tty_port *port,
 
 	/* block if port is in the process of being closed */
 	if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
-		interruptible_sleep_on(&port->close_wait);
+		wait_event_interruptible(port->close_wait,
+				!(port->flags & ASYNC_CLOSING));
 		if (port->flags & ASYNC_HUP_NOTIFY)
 			return -EAGAIN;
 		else