net: bridge: add the multicast_flood flag attribute to brport_attrs

When I added the multicast flood control flag, I also added an attribute
for it for sysfs similar to other flags, but I forgot to add it to
brport_attrs.

Fixes: b6cb5ac8331b ("net: bridge: add per-port multicast flood flag")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_sysfs_if.c

@@ -217,6 +217,7 @@ static const struct brport_attribute *brport_attrs[] = {
 #endif
 	&brport_attr_proxyarp,
 	&brport_attr_proxyarp_wifi,
+	&brport_attr_multicast_flood,
 	NULL
 };