qeth: optimize IP handling in rx_mode callback

In layer3 mode of the qeth driver, multicast IP addresses
from struct net_device and other type of IP addresses
from other sources require mapping to the OSA-card.
This patch simplifies the IP address mapping logic, and changes imple-
mentation of ndo_set_rx_mode callback and ip notifier events.
Addresses are stored in private hashtables instead of lists now.
It allows hardware registration/removal for new/deleted multicast
addresses only.

Signed-off-by: Lakhvich Dmitriy <ldmitriy@ru.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: Evgeny Cherkashin <Eugene.Crosser@ru.ibm.com>
Reviewed-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>