mxrouter: Don't remove vlan interfaces twice

When a vlan interface definition is removed from the configuration,
currently the code attempts to remove the actual vlan interface twice:
once by the general logic ($have_if, $want_if -> unconfigure_if()) and
once by the special logic ($have_vlan, $want_vlan -> unconfigure_vlan()).

Remove the later.

mxrouter/mxrouterctl

@@ -292,18 +292,6 @@ sub read_active_vlans {
 	return ($have_vlan);
 }
 
-sub unconfigure_vlans {
-	my ($have_vlan)=@_;
-
-	for my $device (sort keys %$have_vlan) {
-		sys("ip link set dev $device down");
-	}
-	for my $device (sort keys %$have_vlan) {
-		my ($base_device,$vlan_num)=$device=~/^([^.]+)\.(.+)$/;
-		sys("ip link delete $device");
-	}
-}
-
 sub configure_vlans {
 	my ($want_vlan)=@_;
 	for my $device (sort keys %$want_vlan) {
@@ -514,20 +502,14 @@ sub start {
 
 	my ($have_vlan)=read_active_vlans();
 	delete $have_vlan->{$_} for keys %$want_if;  # vlan interfaces created in main and moved via interface()
-	my ($new_vlan,$del_vlan)=({},{});
+	my $new_vlan = {};
 
 	for (keys %$want_vlan) {
 		$new_vlan->{$_}=$want_vlan->{$_}
 			unless exists $have_vlan->{$_}
 			&& $have_vlan->{$_}[0] eq $want_vlan->{$_}[0]
 			&& $have_vlan->{$_}[1] eq $want_vlan->{$_}[1];
 	}
-	for (keys %$have_vlan) {
-		$del_vlan->{$_}=$have_vlan->{$_}
-			unless exists $want_vlan->{$_}
-			&& $have_vlan->{$_}[0] eq $want_vlan->{$_}[0]
-			&& $have_vlan->{$_}[1] eq $want_vlan->{$_}[1];
-	}
 
 	for (keys %$ip_want_addr) {
 		$new_addr->{$_}=$ip_want_addr->{$_}
@@ -577,7 +559,6 @@ sub start {
 	stop_process_if($process_radvd);
 	unconfigure_route($del_route);
 	unconfigure_ip($del_addr);
-	unconfigure_vlans($del_vlan);
 	unconfigure_if($del_if);
 
 	configure_if($want_if);