Fixes PHP Notice (when saving settings)

NOTICE:
wp-content/plugins/gravityview/includes/lib/edd-redux-extension/extensio
n_edd.php:127 - Undefined index: status
require_once('wp-admin/admin.php'), do_action('admin_init'),
call_user_func_array, ReduxFramework->_register_settings,
do_action('redux/options/gravityview_settings/field/edd_license/register
'), call_user_func_array, ReduxFramework_extension_edd->register