netfilter: Kill unused copies of RCV_SKB_FAIL

This appears to have been a dead macro in both nfnetlink_log.c and
nfnetlink_queue_core.c since these pieces of code were added in 2005.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>