net: ieee802154: forbid monitor for del llsec dev

This patch forbids to del llsec dev for monitor interfaces which we
don't support yet. Otherwise we will access llsec mib which isn't
initialized for monitors.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20210405003054.256017-9-aahringo@redhat.comSigned-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

net/ieee802154/nl802154.c

@@ -1781,6 +1781,9 @@ static int nl802154_del_llsec_dev(struct sk_buff *skb, struct genl_info *info)
 	struct nlattr *attrs[NL802154_DEV_ATTR_MAX + 1];
 	__le64 extended_addr;
 
+	if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR)
+		return -EOPNOTSUPP;
+
 	if (!info->attrs[NL802154_ATTR_SEC_DEVICE] ||
 	    nla_parse_nested_deprecated(attrs, NL802154_DEV_ATTR_MAX, info->attrs[NL802154_ATTR_SEC_DEVICE], nl802154_dev_policy, info->extack))
 		return -EINVAL;