usb_serial: Kill port mutex

The tty port has a port mutex used for all the port related locking so we
don't need the one in the USB serial layer any more.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/opticon.c b/drivers/usb/serial/opticon.c
index 80f59b6..c03fdc02 100644
--- a/drivers/usb/serial/opticon.c
+++ b/drivers/usb/serial/opticon.c
@@ -501,12 +501,12 @@
 	struct usb_serial_port *port = serial->port[0];
 	int result;
 
-	mutex_lock(&port->mutex);
+	mutex_lock(&port->port.mutex);
 	if (port->port.count)
 		result = usb_submit_urb(priv->bulk_read_urb, GFP_NOIO);
 	else
 		result = 0;
-	mutex_unlock(&port->mutex);
+	mutex_unlock(&port->port.mutex);
 	return result;
 }