bridge: netlink: add support for igmp's hash_max

Add IFLA_BR_MCAST_HASH_MAX to allow setting/getting br->hash_max via
netlink.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index ca7ca76..10a44a73 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -250,6 +250,7 @@
 	IFLA_BR_MCAST_QUERY_USE_IFADDR,
 	IFLA_BR_MCAST_QUERIER,
 	IFLA_BR_MCAST_HASH_ELASTICITY,
+	IFLA_BR_MCAST_HASH_MAX,
 	__IFLA_BR_MAX,
 };