bond: Implement a basic set of rtnl link ops

This implements a basic set of rtnl link ops and takes advantage of
the fact that rtnl_link_unregister kills all of the surviving
devices to all us to kill bond_free_all.  A module alias
is added so ip link add can pull in the bonding module.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>