Merge branch 's390-qeth-next'

Julian Wiedmann says:

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s390/net: more updates for 4.14

please apply another batch of qeth patches for net-next.
This reworks the xmit path for L2 OSAs to use skb_cow_head() instead of
skb_realloc_headroom().
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Signed-off-by: David S. Miller <davem@davemloft.net>