From the getopt_long() documentation:

| The argument longopts must be an array of these structures, one for each
| long option. Terminate the array with an element containing all zeros.

Otherwise barebox-state will segfault for unknown options:

  % ./barebox-state --foo
  [1]    17946 segmentation fault (core dumped)  ./barebox-state --foo

Signed-off-by: Enrico Jorns <ejo@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>