mlx4: Implement memory windows allocation and deallocation

Implement MW allocation and deallocation in mlx4_core and mlx4_ib.
Pass down the enable bind flag when registering memory regions.

Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Shani Michaeli <shanim@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>