USB: mos7840: remove NULL-urb submission

The private int_urb is never allocated so the submission from the
control completion handler will always fail. Remove this odd piece of
broken code.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>