Merge branch 's390-qeth-fixes'

Julian Wiedmann says:

====================
s390/qeth: fixes 2019-03-18

please apply the following three patches to -net. The first two are fixes
for minor race conditions in the probe code, while the third one gets
dropwatch working (again).
====================

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