net-bonding: Adding support for throughputs larger than 65536 Mbps

This updates the bonding driver to support v2.6.27-rc3 enhancements
(b11f8d8c aka. "ethtool: Expand ethtool_cmd.speed to 32 bits") which
allow to encode the Mbps link speed on 32-bits (Max 4 Pbps) instead of
16 (Max 65536 Mbps).

This patch also attempts to compact struct slave by reordering its
fields.

Signed-off-by: David Decotigny <decot@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>