OffloadUtils - tcFilterAddDevBpf() - add NLA_F_NESTED to TCA_OPTIONS

The lack of this on a clearly nested attribute appears to be
a result of us reverse engineering (via strace) what the
(apparently buggy) iproute2 'ip' cli command does.

The fact things work even without it appears to be an oversight in the kernel.

They're not meant to, see kernel source in include/net/netlink.h:

static inline struct nlattr *nla_nest_start(struct sk_buff *skb, int attrtype)
{
    return nla_nest_start_noflag(skb, attrtype | NLA_F_NESTED);
}

static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
		   const struct nlattr *nla,
		   const struct nla_policy *policy,
		   struct netlink_ext_ack *extack)
{
    if (!(nla->nla_type & NLA_F_NESTED)) {
	NL_SET_ERR_MSG_ATTR(extack, nla, "NLA_F_NESTED is missing");
	return -EINVAL;
    }

    return __nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy,
	       NL_VALIDATE_STRICT, extack);
}

and lib/nlattr.c:

if (validate & NL_VALIDATE_NESTED) {
	if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) &&
	    !(nla->nla_type & NLA_F_NESTED)) {
	    NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
			"NLA_F_NESTED is missing");
	    return -EINVAL;
	}
	if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY &&
	    pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) {
	    NL_SET_ERR_MSG_ATTR_POL(extack, nla, pt,
			"NLA_F_NESTED not expected");
	    return -EINVAL;
	}
    }

Tested: atest + TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I645c36810b6b30025fa21e2093ef9dee303f3b86