[NETFILTER]: ip{,6}_queue: convert to seq_file interface

I plan to kill ->get_info which means killing proc_net_create().

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>