Fix SHG handling for ARP/ICMPv6 received from BVI in a BD

Fix SHG handling for ARP/ICMPv6 received from BVI in a BD

This change makes sure ARP/ICMPv6 brodcast packets received from
the BVI of a BD can be flooded to all remote VTEPs via its VXLAN
tunnels irrespective of SHG setting. Similar processing was done
for unicast packets already and needs to be extpanded to ARP and
ICMPv6 broadcast packets.

Change-Id: I26ac43ecdbc81a769f742a583a156506f7e70d49
Signed-off-by: John Lo <loj@cisco.com>
(cherry picked from commit c97b4aca0db8d84b17ceb03a14ab44346a2b3466)