Merge branch 'tcp-tcp_v4_err-cleanups'

Eric Dumazet says:

====================
tcp: tcp_v4_err() cleanups

This series is a followup of patch 5fc8c26e2270 ("tcp: tcp_v4_err() icmp
skb is named icmp_skb").

Move the RFC 6069 code into a helper, and rename icmp_skb to standard
skb name so that tcp_v4_err() and tcp_v6_err() are using consistent names.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>