net: fix address check in rtnl_fdb_del

Commit 6681712d
	vxlan: generalize forwarding tables

relaxed the address checks in rtnl_fdb_del() to use is_zero_ether_addr().
This allows users to add multicast addresses using the fdb API.  However,
the check in rtnl_fdb_del() still uses a more strict
is_valid_ether_addr() which rejects multicast addresses.  Thus it
is possible to add an fdb that can not be later removed.
Relax the check in rtnl_fdb_del() as well.
Signed-off-by: NVlad Yasevich <vyasevic@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -2192,7 +2192,7 @@ static int rtnl_fdb_del(struct sk_buff *skb, struct nlmsghdr *nlh)
 	}
 
 	addr = nla_data(tb[NDA_LLADDR]);
-	if (!is_valid_ether_addr(addr)) {
+	if (is_zero_ether_addr(addr)) {
 		pr_info("PF_BRIDGE: RTM_DELNEIGH with invalid ether address\n");
 		return -EINVAL;
 	}