call security_groups_member_updated in port_update

When a running VM is added to a security group, all existing VMs (ports)
in the security group should be notified/updated - otherwise they would
have incorrect rules, not knowing the new VM/port added.

The current behavior would only update the port of the added VM. This
patch forces an security_groups_member_updated() call for all the
security groups that have ports removed or added.

Change-Id: Ibdcd74f47043762386b62f3ec0fa1723060446ac
Closes-Bug: 1316618
Merge "call security_groups_member_updated in port_update"