IB/mlx4_ib: Add support for user MR re-registration

This enables the user to change the protection domain, access flags
and translation (address and length) of the MR.

Use basic mlx4_core helper functions to get, update and set MPT and
MTT objects according to the required modifications.

Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>