IB/mlx5: Set uid as part of DCT commands

Set uid as part of DCT create command so that the firmware can
manage the DCT object in a secured way.

The uid for the destroy and drain commands are set by mlx5_core.

That will enable using a DCT that was created by verbs application
to be used by the DEVX flow in case the uid is equal.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>