Add an auxiliary virtual bus to model the mlx4 driver structure. The
code is added along the current custom device management logic.
Subsequent patches switch mlx4_en and mlx4_ib to the auxiliary bus and
the old interface is then removed.

Structure mlx4_priv gains a new adev dynamic array to keep track of its
auxiliary devices. Access to the array is protected by the global
mlx4_intf mutex.

Functions mlx4_register_device() and mlx4_unregister_device() are
updated to expose auxiliary devices on the bus in order to load mlx4_en
and/or mlx4_ib. Functions mlx4_register_auxiliary_driver() and
mlx4_unregister_auxiliary_driver() are added to substitute
mlx4_register_interface() and mlx4_unregister_interface(), respectively.
Function mlx4_do_bond() is adjusted to walk over the adev array and
re-adds a specific auxiliary device if its driver sets the
MLX4_INTFF_BONDING flag.
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Tested-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Acked-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>