Packet sockets may call dev_header_parse with NULL daddr. Make
lowpan_header_ops.create fail.
Fixes: 87a93e4eceb4 ("ieee802154: change needed headroom/tailroom") Signed-off-by: Willem de Bruijn <[email protected]> Acked-by: Alexander Aring <[email protected]> Signed-off-by: David S. Miller <[email protected]>