Changed field name and add validation

<input id="ninja_forms_field_<?php echo $field_id;?>" data-mask="<?php
echo $mask;?>" data-input-limit="<?php echo $input_limit;?>"
data-input-limit-type="<?php echo $input_limit_type;?>"
data-input-limit-msg="<?php echo $input_limit_msg;?>"
name="ninja_forms_field_<?php echo $field_id;?>" type="text"
class="<?php echo $field_class;?> <?php echo $mask_class;?>"
value="<?php echo $default_value;?>" rel="<?php echo $field_id;?>" />