Use mlx5core to create/destroy all Dynamically Connected Targets, DCTs.

To prevent a hardware memory leak when a DEVX DCT object is destroyed
without calling drain DCT before, (e.g. under cleanup flow), need to
manage its creation and destruction via mlx5 core.

Linux commit:
c5ae1954c47d3fd8815bd5a592aba18702c93f33

MFC after: 1 week
Sponsored by: Mellanox Technologies // NVIDIA Networking