qeth: keep ip-address after LAN_OFFLINE failure

Problem:     If setting of an ip-address fails with LAN_OFFLINE,
             qeth does not save the ip-address in its internal
             list of set ip-addresses. qeth recovers after a
             following STARTLAN event, but cannot set the unsaved
             ip-address.
Solution:    save the ip-address in the qeth-maintained list of
             ip-addresses after a LAN_OFFLINE failure for SETIP.

Signed-off-by: Ursula Braun <braunu@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>