net: bridge: add neigh_suppress to bridge port policies

Add an entry for IFLA_BRPORT_NEIGH_SUPPRESS to bridge port policies.

Fixes: 821f1b21 ("bridge: add new BR_NEIGH_SUPPRESS port flag to suppress arp and nd flood")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>