tty: USB does not need the filp argument in the drivers

And indeed none of them use it. Clean this up as it will make moving to a
standard open method rather easier.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 31c7a09..3dda684 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -244,7 +244,7 @@
 
 		/* only call the device specific open if this
 		 * is the first time the port is opened */
-		retval = serial->type->open(tty, port, filp);
+		retval = serial->type->open(tty, port);
 		if (retval)
 			goto bailout_interface_put;
 		mutex_unlock(&serial->disc_mutex);