Fix IPv6 RA security group rule for DVR

Current IPv6 RA security group rule doesn't work for
DVR because the code only allows RA from device_owner
is network:router_interface. When DVR is enabled, the
router interface is network:router_interface_distributed.

This fix fixes the RA rule to allow RA from DVR router
interface, so router advertisement from DVR RADVD can
pass to VM.

Co-Authored-By: Baodong (Robert) Li <baoli@cisco.com>

Change-Id: Idd1324c653dcb15f5dacf2d897a7048bca22fc38
Partial-Bug: 1376325
Merge "Fix IPv6 RA security group rule for DVR"