Merge branch 's390-qeth-fixes'

Julian Wiedmann says:

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s390/qeth: fixes 2020-03-11

please apply the following patch series for qeth to netdev's net tree.

Just one fix to get the RX buffer pool resizing right, with two
preparatory cleanups.
This is on the larger side given where we are in the -rc cycle, but a
big chunk of the delta is just refactoring to make the fix look nice.

I intentionally split these off from yesterday's series. No objections
if you'd rather punt them to net-next, the series should apply cleanly.
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Signed-off-by: David S. Miller <davem@davemloft.net>