Fix double sizeof when parsing IPv6 address from
user space because it breaks get/del by specific IPv6 address.
	Problem noticed by David Binderman:
https://bugzilla.kernel.org/show_bug.cgi?id=49171
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
        }
        a = info->attrs[TCP_METRICS_ATTR_ADDR_IPV6];
        if (a) {
-               if (nla_len(a) != sizeof(sizeof(struct in6_addr)))
+               if (nla_len(a) != sizeof(struct in6_addr))
                        return -EINVAL;
                addr->family = AF_INET6;
                memcpy(addr->addr.a6, nla_data(a), sizeof(addr->addr.a6));