firewall: adopt formatting of RFC 1918 and IANA rules

Adopt style of RFC 1918 rule and reserved IANA rule to match user created
rules in style.

src/www/firewall_rules.php

@@ -319,14 +319,14 @@ $( document ).ready(function() {
               if (isset($config['interfaces'][$selected_if]['blockbogons'])): ?>
                   <tr valign="top" id="frrfc1918">
                     <td>&nbsp;</td>
-                    <td align="center"><span class="glyphicon glyphicon-remove text-danger"></span></td>
+                    <td><span class="glyphicon glyphicon-remove text-danger"></span></td>
                     <td>*</td>
                     <td><?=gettext("Reserved/not assigned by IANA");?></td>
                     <td class="hidden-xs hidden-sm">*</td>
                     <td class="hidden-xs hidden-sm">*</td>
                     <td class="hidden-xs hidden-sm">*</td>
                     <td class="hidden-xs hidden-sm">*</td>
-                    <td class="hidden-xs hidden-sm">*</td>
+                    <td class="hidden-xs hidden-sm">&nbsp;</td>
                     <td><?=gettext("Block bogon networks");?></td>
                     <td>
                       <a href="interfaces.php?if=<?=htmlspecialchars($if)?>#rfc1918" title="<?=gettext("edit rule");?>" class="btn btn-default btn-xs"><span class="glyphicon glyphicon-pencil"></span></a>