enic: Fix address deregistration for sriov vf during port profile disassociate

This patch fixes erroneous PF address deregistration in cases where
a port profile disassociate is called on an already disassociated interface.

Signed-off-by: Roopa Prabhu <roprabhu@cisco.com>
Signed-off-by: Christian Benvenuti <benve@cisco.com>
Signed-off-by: sujith sankar <ssujith@cisco.com>
Signed-off-by: ChingWei Chang <cwchang@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>