net: parameterize the removing client from nc list

net: parameterize the removing client from nc list

This change is used in later commits so we can avoid the removal of the
netclient if it is delayed.

No functional change intended.

Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
(cherry picked from commit db0d4017f9b9e87f962b35dd19a4912bbfcd3cbc)
(Mjt: pick this one up for the following change,
 "net: move backend cleanup to NIC cleanup")
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>