[VLAN]: Proc entry is not renamed when vlan device name changes.

This may lead to situations, when each of two proc entries produce
data for the other's device.

Looks like a BUG, so this patch is for net-2.6. It will not apply to
net-2.6.26 since dev->nd_net access is replaced with dev_net(dev)
one.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>