s390/qeth: shrink qeth_ipaddr struct

Using up 8 bytes in every ipaddr object to store SETIP/DELIP flags is
rather wasteful. Except for takeover eligibility, the flag values all
just depend on the address type, so determine them on demand.

While at it reorder the struct to fill an alignment hole.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>