IB/mlx5: Enhance UMR support to allow partial page table update

The current UMR interface doesn't allow partial updates to a memory
region's page tables. This patch changes the interface to allow that.

It also changes the way the UMR operation validates the memory
region's state.  When set, IB_SEND_UMR_FAIL_IF_FREE will cause the UMR
operation to fail if the MKEY is in the free state. When it is
unchecked the operation will check that it isn't in the free state.

Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Shachar Raindel <raindel@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>