Add few helper functions to support a mechanism of getting an MPT,
modifying it and updating the HCA with the modified object.

The code takes 2 paths, one for directly changing the MPT (and
sometimes its related MTTs) and another one which queries the MPT and
updates the HCA via fw command SW2HW_MPT. The first path is used in
native mode; the second path is slower and is used only in SRIOV.
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>