Merge branch 's390-next'

Julian Wiedmann says:

====================
s390/net: updates 2018-04-26

please apply the following patches to net-next. There's the usual
cleanups & small improvements, and Kittipon adds HW offload support
for IPv6 checksumming.
====================

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