vlan: Use is_vlan_dev()

Use simplified is_vlan_dev function.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index b529110..8141e2d 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -570,8 +570,7 @@
 			goto out;
 
 		err = -EINVAL;
-		if (args.cmd != ADD_VLAN_CMD &&
-		    !(dev->priv_flags & IFF_802_1Q_VLAN))
+		if (args.cmd != ADD_VLAN_CMD && !is_vlan_dev(dev))
 			goto out;
 	}
 
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 4a85259..88f318a 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -694,7 +694,7 @@
 		dev->hard_start_xmit = vlan_dev_hard_start_xmit;
 	}
 
-	if (real_dev->priv_flags & IFF_802_1Q_VLAN)
+	if (is_vlan_dev(real_dev))
 		subclass = 1;
 
 	lockdep_set_class_and_subclass(&dev->_xmit_lock,
diff --git a/net/8021q/vlanproc.c b/net/8021q/vlanproc.c
index 08b54b5..6073a88 100644
--- a/net/8021q/vlanproc.c
+++ b/net/8021q/vlanproc.c
@@ -290,7 +290,7 @@
 	static const char fmt[] = "%30s %12lu\n";
 	int i;
 
-	if (!(vlandev->priv_flags & IFF_802_1Q_VLAN))
+	if (!is_vlan_dev(vlandev))
 		return 0;
 
 	seq_printf(seq,