[NETFILTER]: Use pskb_trim in {ip,ip6,nfnetlink}_queue

Based on patch by James D. Nurmi:

I've got some code very dependant on nfnetlink_queue, and turned up a
large number of warns coming from skb_trim.  While it's quite possibly
my code, having not seen it on older kernels made me a bit suspect.

Anyhow, based on some googling I turned up this thread:
http://lkml.org/lkml/2006/8/13/56



And believe the issue to be related, so attached is a small patch to
the kernel -- not sure if this is completely correct, but for anyone
else hitting the WARN_ON(1) in skbuff.h, it might be helpful..

Signed-off-by: James D. Nurmi <jdnurmi@gmail.com>

Ported to ip6_queue and nfnetlink_queue and added return value
checks.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>