tty_port,usb-console: Fix usb serial console open/close regression

Commit e1108a63e10d344284011cccc06328b2cd3e5da3 ("usb_serial: Use the
shutdown() operation") breaks the ability to use a usb console
starting in 2.6.33.  This was observed when using
console=ttyUSB0,115200 as a boot argument with an FTDI device.  The
error is:

ftdi_sio ttyUSB0: ftdi_submit_read_urb - failed submitting read urb, error -22

The handling of the ASYNCB_INITIALIZED changed in 2.6.32 such that in
tty_port_shutdown() it always clears the flag if it is set.  The fix
is to add a variable to the tty_port struct to indicate when the tty
port is a console.

CC: Alan Cox <alan@linux.intel.com>
CC: Alan Stern <stern@rowland.harvard.edu>
CC: Oliver Neukum <oliver@neukum.org>
CC: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index be492dd..a3bd1d0 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -119,7 +119,7 @@
 static void tty_port_shutdown(struct tty_port *port)
 {
 	mutex_lock(&port->mutex);
-	if (port->ops->shutdown &&
+	if (port->ops->shutdown && !port->console &&
 		test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags))
 			port->ops->shutdown(port);
 	mutex_unlock(&port->mutex);