ipvs: fix inability to remove a mixed-family RS

The current code prevents any operation with a mixed-family dest
unless IP_VS_CONN_F_TUNNEL flag is set. The problem is that it's impossible
for the client to follow this rule, because ip_vs_genl_parse_dest does
not even read the destination conn_flags when cmd = IPVS_CMD_DEL_DEST
(need_full_dest = 0).

Also, not every client can pass this flag when removing a dest. ipvsadm,
for example, does not support the "-i" command line option together with
the "-d" option.

This change disables any checks for mixed-family on IPVS_CMD_DEL_DEST command.
Signed-off-by: Alexey Andriyanov <alan@al-an.info>
Fixes: bc18d37f ("ipvs: Allow heterogeneous pools now that we support them")
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

net/netfilter/ipvs/ip_vs_ctl.c

@@ -3399,7 +3399,7 @@ static int ip_vs_genl_set_cmd(struct sk_buff *skb, struct genl_info *info)
 		if (udest.af == 0)
 			udest.af = svc->af;
 
-		if (udest.af != svc->af) {
+		if (udest.af != svc->af && cmd != IPVS_CMD_DEL_DEST) {
 			/* The synchronization protocol is incompatible
 			 * with mixed family services
 			 */