vlan: Invoke driver vlan hooks only if device is present

NIC drivers mark device as detached during error recovery.
It expects no manangement hooks to be invoked in this state.
Invoke driver vlan hooks only if device is present.

Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@avagotech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>