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/ipw.c b/drivers/usb/serial/ipw.c
index 29ad038..727d323 100644
--- a/drivers/usb/serial/ipw.c
+++ b/drivers/usb/serial/ipw.c
@@ -193,8 +193,7 @@
 	return;
 }
 
-static int ipw_open(struct tty_struct *tty,
-			struct usb_serial_port *port, struct file *filp)
+static int ipw_open(struct tty_struct *tty, struct usb_serial_port *port)
 {
 	struct usb_device *dev = port->serial->dev;
 	u8 buf_flow_static[16] = IPW_BYTES_FLOWINIT;