(legacy) fix interface selection on post issues in floating rules, firewall_rules_edit.php

(cherry picked from commit 74d923fd)

src/www/firewall_rules_edit.php

@@ -778,7 +778,13 @@ include("head.inc");
 <?php
                     endif;
                     foreach (formInterfaces() as $iface => $ifacename): ?>
-                        <option value="<?=$iface;?>" <?= !empty($pconfig['interface']) && ($iface == $pconfig['interface'] || (!is_array($pconfig['interface']) && strpos($pconfig['interface'], ',') !== false && in_array($iface, explode(',', $pconfig['interface'])))) ? 'selected="selected"' : ''; ?>>
+                        <option value="<?=$iface;?>"
+                            <?= !empty($pconfig['interface']) && (
+                                  $iface == $pconfig['interface'] ||
+                                  // match floating / multiple interfaces
+                                  (!is_array($pconfig['interface']) && in_array($iface, explode(',', $pconfig['interface']))) ||
+                                  (is_array($pconfig['interface']) && in_array($iface, $pconfig['interface']))
+                                ) ? 'selected="selected"' : ''; ?>>
                           <?=htmlspecialchars($ifacename);?>
                         </option>
 <?php