interfaces: kill is_jumbo_capable()

Introduced in 2005 to separate good VLAN-capable driver from
the bad ones.  We wonder how relevant this is nowadays.

Breaks at least Xen where the driver fails to pass the host's
VLAN capabilities.

Discussed with: @AdSchellevis

src/etc/inc/console.inc

@@ -489,11 +489,9 @@ EOD;
         } else {
             $vlan_capable=0;
             foreach ($iflist as $iface => $ifa) {
-                if (is_jumbo_capable($iface)) {
-                    echo sprintf("% -8s%s%s\n", $iface, $ifa['mac'],
-                        $ifa['up'] ? "   (up)" : "");
-                    $vlan_capable++;
-                }
+                echo sprintf("% -8s%s%s\n", $iface, $ifa['mac'],
+                    $ifa['up'] ? "   (up)" : "");
+                $vlan_capable++;
             }
         }
 
@@ -506,8 +504,7 @@ EOD;
         $vlan['if'] = chop(fgets($fp));
 
         if ($vlan['if']) {
-            if (!array_key_exists($vlan['if'], $iflist) or
-                !is_jumbo_capable($vlan['if'])) {
+            if (!array_key_exists($vlan['if'], $iflist)) {
                 printf("\nInvalid interface name '%s'\n", $vlan['if']);
                 continue;
             }

src/etc/inc/interfaces.inc

@@ -4451,14 +4451,6 @@ function get_interface_mac($interface)
     return $macinfo["macaddr"];
 }
 
-function is_jumbo_capable($iface)
-{
-    $intf_details = legacy_interface_details(trim($iface));
-
-    return isset($intf_details['capabilities']) &&
-        in_array('vlan_mtu', $intf_details['capabilities']);
-}
-
 function get_vip_descr($ipaddress)
 {
     global $config;

src/www/interfaces_qinq_edit.php

@@ -155,10 +155,7 @@ interface_qinq_configure($qinqentry);
                               $portlist[$lagg['laggif']] = $lagg;
                           }
                       }
-                      foreach ($portlist as $ifn => $ifinfo):
-                        if (!is_jumbo_capable($ifn)) {
-                            continue;
-                        }?>
+                      foreach ($portlist as $ifn => $ifinfo): ?>
                         <option value="<?=$ifn;?>" <?=$ifn == $pconfig['if'] ? " selected=\"selected\"" : "";?>>
                           <?=htmlspecialchars($ifn);?>  ( <?= !empty($ifinfo['mac']) ? $ifinfo['mac'] :"" ;?> )
                         </option>

src/www/interfaces_vlan_edit.php

@@ -174,10 +174,7 @@ interface_configure($confif);
                               $portlist[$lagg['laggif']] = $lagg;
                           }
                       }
-                      foreach ($portlist as $ifn => $ifinfo):
-                        if (!is_jumbo_capable($ifn)) {
-                            continue;
-                        }?>
+                      foreach ($portlist as $ifn => $ifinfo): ?>
                         <option value="<?=$ifn;?>" <?=$ifn == $pconfig['if'] ? " selected=\"selected\"" : "";?>>
                           <?=htmlspecialchars($ifn);?>
                           ( <?= !empty($ifinfo['mac']) ? $ifinfo['mac'] :"" ;?> )