[NETFILTER]: Revert nf_reset change

Revert the nf_reset change that caused so much trouble, drop conntrack
references manually before packets are queued to packet sockets.

Signed-off-by: Phil Oester <kernel@linuxace.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>