Remove needless variable check from fboauth_block_view()

fboauth_block_view() checks if the $app_id variable exists but this is not defined in the current scope. This probably is some leftover cruft.

Also $delta is not used, but as this is part of the standard hook implementation this should perhaps not be removed.

function fboauth_block_view($delta) {
  $block = array();
  $app_id = isset($app_id) ? $app_id : variable_get('fboauth_id', '');
  if ($app_id && !fboauth_fbid_load()) {
    $block['content'] = fboauth_action_display('connect');
  }
  return $block;
}