This patch adds buffer address regist/unregistration routine.

This function is mainly invoked when network device's
activation (open) and deactivation (close)
in order to retist/unregist shared buffer address.
Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>