staging: octeon-usb: use usb_hcd_link_urb_to_ep()

The driver did not use link_urb_to_ep() / unlink_urb_from_ep(). This
caused odd behaviour in some error recovery situations, all requests
would start to fail after the first failure.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>