s390/qeth: don't let HW override the configured port role

The only time that our Bridgeport role should change is when we change
the configuration ourselves. In which case we also adjust our internal
state tracking, no need to do it again when we receive the corresponding
event.

Removing the locked section helps a subsequent patch that needs to flush
the workqueue while under sbp_lock.

It would be nice to raise a warning here in case HW does weird things
after all, but this could end up generating false-positives when we
change the configuration ourselves.

Suggested-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>