Merge branch 'erspan-use-after-free'

Lorenzo Bianconi says:

====================
fix possible use-after-free in erspan_v{4,6}

Similar to what I did in commit bb9bd814ebf0 ("ipv6: sit: reset ip
header pointer in ipip6_rcv"), fix possible use-after-free in
erspan_rcv and ip6erspan_rcv extracting tunnel metadata since the
packet can be 'uncloned' running __iptunnel_pull_header
====================

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