tty: Remove ASYNC_CLOSING

The tty core no longer provides nor uses ASYNC_CLOSING; remove from
tty_port_close_start() and tty_port_close_end() as well as tty drivers
which open-code these state changes. Unfortunately, even though the
bit is masked from userspace, its inclusion in a uapi header precludes
removing the macro.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: linux-cris-kernel@axis.com
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 0473fc7..dbcca30 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -476,7 +476,6 @@
 		spin_unlock_irqrestore(&port->lock, flags);
 		return 0;
 	}
-	set_bit(ASYNCB_CLOSING, &port->flags);
 	spin_unlock_irqrestore(&port->lock, flags);
 
 	tty->closing = 1;
@@ -515,7 +514,7 @@
 		spin_lock_irqsave(&port->lock, flags);
 		wake_up_interruptible(&port->open_wait);
 	}
-	port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_CLOSING);
+	port->flags &= ~ASYNC_NORMAL_ACTIVE;
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 EXPORT_SYMBOL(tty_port_close_end);