bridge: Fix IPv6 multicast snooping by storing correct protocol type

The protocol type for IPv6 entries in the hash table for multicast
bridge snooping is falsely set to ETH_P_IP, marking it as an IPv4
address, instead of setting it to ETH_P_IPV6, which results in negative
look-ups in the hash table later.
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_multicast.c

@@ -784,7 +784,7 @@ static int br_ip6_multicast_add_group(struct net_bridge *br,
 		return 0;
 
 	ipv6_addr_copy(&br_group.u.ip6, group);
-	br_group.proto = htons(ETH_P_IP);
+	br_group.proto = htons(ETH_P_IPV6);
 
 	return br_multicast_add_group(br, port, &br_group);
 }