IPv6 Router Advertisements are blocked in secgroups when using radvd based networks

Description of problem:
=======================
Discovered in: https://bugzilla.redhat.com/show_bug.cgi?id=1173987

I Created n radvd IPv6 subnet with:
1. ipv6_ra_mode: dhcpv6-stateless
2. ipv6_address_mode: dhcpv6-stateless

Version-Release number of selected component (if applicable):
=============================================================
openstack-neutron-2014.2.1-2

How reproducible:
=================
100%

Steps to Reproduce:
===================
1. Create an IPv4 neutron network (might not be mandatory but this is how I did it):
   # neutron net-create internal_ipv4_a --shared

2. Create an IPv4 subnet:
   # neutron subnet-create <IPv4_net_id> 192.168.1.0/24 --name internal_ipv4_a_subnet --ip-version 4

3. Create an IPv6 neutron network:
   # neutron net-create tenant_a_radvd_stateless --shared --provider:network_type=gre --provider:segmentation_id=123

4. Create an IPv6 subnet:
   # neutron subnet-create <IPv6_net_id> 2001:1234:1234::/64 --name internal_ipv6_subnet --ipv6-ra-mode dhcpv6-stateless --ipv6-address-mode dhcpv6-stateless --dns-nameserver 2001:4860:4860::8888 --ip-version 6

5. Create a neutron router:
   # neutron router-create router1

6. Attach subnets to the router
   # neutron router-interface-add <router_id> <ipv4_subnet>
   # neutron router-interface-add <router_id> <ipv6_subnet>

7. boot an instance with that network
   # nova boot tenant_a_instance_radvd_stateless --flavor m1.small --image <image_id> --key-name keypair --security-groups default --nic net-id=<ipv4_net_id> --nic net-id=<ipv6_net_id>

Actual results:
===============
1. RAs reach the instance qbr but not to the instance tap device.
2. Instance did not obtain IPv6 address.

Expected results:
=================
IPv6 Router Advertisements should reach the instance.

Additional info:
================
1. Compute node and L3 agent deployed on different servers.
2. Communication between the nodes (RAs) done via GRE tunnels.
3. This worked before openstack-neutron-2014.2-11
4. Tested with RHEL7