Merge branch 's390-qeth-next'

Julian Wiedmann says:

====================
s390/qeth: updates 2020-03-27

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

Spring clean edition:
- remove one sysfs attribute that was never put in use,
- make support for OSN and OSX devices optional, and
- probe for removal of the obsolete OSN support.
====================

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