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>

drivers/usb/serial/keyspan_pda.c

@@ -681,7 +681,7 @@ static int keyspan_pda_carrier_raised(struct usb_serial_port *port)
 
 
 static int keyspan_pda_open(struct tty_struct *tty,
-			struct usb_serial_port *port, struct file *filp)
+					struct usb_serial_port *port)
 {
 	struct usb_serial *serial = port->serial;
 	unsigned char room;