[NETFILTER]: nf_queue: fix end-of-list check

The comparison wants to find out if the last list iteration reached the
end of the list. It needs to compare the iterator with the list head to
do this, not the element it is looking for.

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