Merge branch 's390-qeth-updates'

Julian Wiedmann says:

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s390/qeth: updates 2018-07-19

please apply one more round of qeth patches to net-next.
This brings additional performance improvements for the transmit code,
and some refactoring to pave the way for using netdev_priv.
Also, two minor fixes for rare corner cases.
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Signed-off-by: David S. Miller <davem@davemloft.net>