IB/mlx4: Support memory window binding

* Implement memory windows binding in mlx4_ib_post_send.

* Implement mlx4_ib_bind_mw by deferring to mlx4_ib_post_send.

* Rename MLX4_WQE_FMR_PERM_* flags to MLX4_WQE_FMR_AND_BIND_PERM_*,
  indicating that they are used both for fast registration work
  requests, and for memory window bind work requests.

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>