USB: option close race

the option driver does not directly use usb_kill_urb(). It uses a wrapper.
This wrapper means that callbacks which are running are not killed during
close, resubmitting and illicitly pushing data into the tty layer.
The whole purpose of usb_kill_urb() is subverted. The wrapper must be removed.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Matthias Urlichs <smurf@smurf.noris.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>