bonding: sync netpoll code with bridge

V4: rebase to net-next-2.6
V3: remove an useless #ifdef.

This patch unifies the netpoll code in bonding with netpoll code in bridge,
thanks to Herbert that code is much cleaner now.

Signed-off-by: WANG Cong <amwang@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>